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kaidulkaidul
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515/564 problems solved
1 parent 5442017 commit e22be69

12 files changed

+732
-427
lines changed

‎README.md

+438-427
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‎source-code/Complex_Number_Multiplication.cpp

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class Solution {
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#define real first
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#define img second
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pair<int, int> tokenize(string const& s) {
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int plus = s.find('+');
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assert(plus != string::npos);
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int real = atoi(s.substr(0, plus).c_str());
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int img = atoi(s.substr(plus + 1, s.length() - plus - 2).c_str());
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return {real, img};
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}
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public:
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string complexNumberMultiply(string a, string b) {
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pair<int, int> complexA = tokenize(a);
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pair<int, int> complexB = tokenize(b);
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int real = complexA.real * complexB.real + complexA.img * complexB.img * (-1);
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int img = complexA.real * complexB.img + complexA.img * complexB.real;
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return to_string(real) + "+" + to_string(img) + "i";
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}
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};

‎source-code/Friend_Circles.cpp

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class Solution {
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void dfs(int u, vector<vector<int>> const& M, vector<bool>& visited) {
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visited[u] = true;
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for(int i = 0; i < (int)M[u].size(); i++) {
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if(!M[u][i] or visited[i]) {
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continue;
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}
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dfs(i, M, visited);
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}
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}
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public:
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int findCircleNum(vector<vector<int>>& M) {
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int n = (int)M.size();
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vector<bool> visited(n, false);
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int circle = 0;
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for(int i = 0; i < n; i++) {
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if(!visited[i]) {
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circle++;
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dfs(i, M, visited);
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}
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}
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return circle;
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}
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};

‎source-code/Longest_Uncommon_Subsequence_I.cpp

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class Solution {
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public:
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int findLUSlength(string a, string b) {
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return (a != b) ? (int)max(a.length(), b.length()) : -1;
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}
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};

‎source-code/Longest_Uncommon_Subsequence_II.cpp

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class Solution {
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bool isSubseq(string const& s1, string const& s2) {
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if(s1.length() > s2.length()) {
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return false;
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}
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int j = 0;
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for(int i = 0; i < (int)s2.length() and j < (int)s1.length(); i++) {
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if(s2[i] == s1[j]) {
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j++;
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}
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}
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return j == (int)s1.length();
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}
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public:
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int findLUSlength(vector<string>& strs) {
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int result = -1;
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unordered_set<string> exist;
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for(int i = 0; i < (int)strs.size(); i++) {
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// silly prune
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if(exist.find(strs[i]) != exist.end() or (int)strs[i].length() <= result) {
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continue;
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}
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bool flag = true;
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for(int j = 0; j < (int)strs.size() and flag; j++) {
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if(i == j) continue;
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if(isSubseq(strs[i], strs[j])) {
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flag = false;
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}
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}
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exist.insert(strs[i]);
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if(flag) {
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result = max(result, (int)strs[i].length());
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}
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}
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return result;
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}
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};

‎source-code/Next_Greater_Element_III.cpp

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class Solution {
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public:
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int nextGreaterElement(int n) {
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string s = to_string(n);
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int m = (int)s.length();
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int k = m - 1;
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for(int i = m - 1; i > 0; i--) {
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if(s[i - 1] < s[i]) {
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k = i - 1;
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break;
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}
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}
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for(int i = m - 1; i > k; i--) {
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if(s[i] > s[k]) {
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swap(s[i], s[k]);
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break;
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}
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}
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reverse(s.begin() + k + 1, s.end());
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long long result = 0LL;
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for(int i = 0; i < m; i++) {
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int digit = s[i] - '0';
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result *= 10;
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result += digit;
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}
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if((int)result == n or result < INT_MIN or result > INT_MAX) {
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return -1;
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}
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return (int)result;
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}
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};

‎source-code/Perfect_Number.cpp

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class Solution {
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public:
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bool checkPerfectNumber(int num) {
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if(num == 1) return 0;
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int sum = 0;
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sum += 1;
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for(int i = 2; i <= sqrt(num); i++) {
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if(num % i == 0) {
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sum += i;
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sum += num / i;
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}
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}
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return num == sum;
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}
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};

‎source-code/Reshape_the_Matrix.cpp

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class Solution {
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public:
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vector<vector<int>> matrixReshape(vector<vector<int>>& nums, int r, int c) {
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int rows = (int)nums.size();
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int cols = (int)nums[0].size();
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if (r * c != rows * cols) {
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return nums;
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}
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vector<vector<int>> reshapedMatrix(r, vector<int>(c));
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for(int i = 0, x = 0, y = 0; i < rows; i++) {
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for(int j = 0; j < cols; j++) {
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reshapedMatrix[x][y++ % c] = nums[i][j];
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if(y % c == 0) {
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x++;
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}
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}
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}
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return reshapedMatrix;
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}
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};

‎source-code/Reverse_Words_in_a_String_III.cpp

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class Solution {
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public:
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string reverseWords(string s) {
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int i = 0, left = 0;
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int n = (int)s.length();
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while(i < n) {
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if(s[i] == ' ' or s[i] == '\n') {
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reverse(s.begin() + left, s.begin() + i);
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left = i + 1;
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}
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i++;
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}
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reverse(s.begin() + left, s.end());
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return s;
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}
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};

‎source-code/Student_Attendance_Record_I.cpp

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class Solution {
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public:
3+
bool checkRecord(string s) {
4+
int consLate = 0, late = 0, absent = 0;
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for(int i = 0; i < (int)s.length(); i++) {
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if(s[i] == 'A') {
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absent++;
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late = 0;
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} else if(s[i] == 'L') {
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late++;
11+
consLate = max(consLate, late);
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} else {
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late = 0;
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}
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}
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return consLate <= 2 and absent < 2;
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}
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};

‎source-code/Student_Attendance_Record_II.cpp

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// TLE
2+
class Solution {
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const static int MOD = 1000000007;
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vector<int> fact;
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vector<int> ifact;
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int power(int base, int exp, int mod) {
8+
if(exp == 0) return 1;
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int ret = power(base, exp / 2, mod) % mod;
10+
ret = 1LL * ret * ret % mod;
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if(exp & 1) {
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ret = 1LL * ret * base % mod;
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}
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return ret;
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}
16+
17+
int modInv(int base, int mod = MOD) {
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return power(base, mod - 2, mod);
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}
20+
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void init(int n) {
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fact = vector<int>(n + 1, 0);
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ifact = vector<int>(n + 1, 0);
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fact[0] = ifact[0] = 1;
25+
for(int i = 1; i <= n; i++) {
26+
fact[i] = 1LL * i * fact[i - 1] % MOD;
27+
ifact[i] = modInv(fact[i]);
28+
}
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}
30+
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int nCr(int n, int r) {
32+
if(r > n) return 0;
33+
int ans = fact[n];
34+
ans = 1LL * ans * ifact[r] % MOD;
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ans = 1LL * ans * ifact[n - r] % MOD;
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return ans;
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}
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public:
39+
int checkRecord(int n) {
40+
init(n + 1);
41+
int maxLate = n - (n / 3);
42+
int result = 0;
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for(int i = 0; i <= maxLate; i++) {
44+
int ways = 0;
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for(int k = (i / 2) + (i % 2), pair = i / 2; k <= i; k++, pair--) {
46+
ways = (ways + (1LL * nCr(n - i + 1, k) * nCr(k, pair)) % MOD) % MOD;
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}
48+
result = (result + ways) % MOD;
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result = (result + (1LL * ways * (n - i) % MOD)) % MOD;
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}
51+
return result;
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}
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};
54+
55+
// MLE
56+
class Solution {
57+
#define MOD 1000000007
58+
vector<vector<vector<int>>> dp;
59+
int n;
60+
61+
int solve(int i, int k, int taken) {
62+
if(i == n) {
63+
return (k == 0);
64+
}
65+
if(dp[i][k][taken] != -1) {
66+
return dp[i][k][taken];
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}
68+
if(taken == 2) {
69+
return dp[i][k][taken] = solve(i + 1, k, 0) % MOD;
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}
71+
72+
return dp[i][k][taken] = (solve(i + 1, k, 0) + (k > 0 ? solve(i + 1, k - 1, taken + 1) : 0)) % MOD;
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}
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public:
76+
int checkRecord(int n) {
77+
this->n = n;
78+
int maxLate = n - (n / 3);
79+
dp= vector<vector<vector<int>>>(n, vector<vector<int>>(maxLate + 1, vector<int>(3, -1)));
80+
int result = 0;
81+
for(int i = 0; i <= maxLate; i++) {
82+
int cnt = solve(0, i, 0);
83+
result = (result + cnt) % MOD;
84+
result = (result + (1LL * cnt * (n - i) % MOD)) % MOD;
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}
86+
return result;
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}
88+
};

‎source-code/Subarray_Sum_Equals_K.cpp

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class Solution {
2+
public:
3+
int subarraySum(vector<int>& nums, int k) {
4+
unordered_map<int, int> freq;
5+
int n = (int)nums.size();
6+
int sum = 0;
7+
freq[sum]++;
8+
int cnt = 0;
9+
for(int i = 0; i < n; i++) {
10+
sum += nums[i];
11+
cnt += freq[sum - k];
12+
freq[sum]++;
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}
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return cnt;
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}
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};

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