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47 changes: 47 additions & 0 deletions Dynamic Programming/LongestPalindromicSubsequence-DP.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
// Author : Ritik Patil
// Date : 11/10/2022
// Time : 23:19
// Description : Added Famous OA round question with help of DP
/*Given A string, find the length of longest palindrome present in the string .*/

#include <bits/stdc++.h>
using namespace std;

/* Returns length of longest Palindrome Subsequence for a string */
int longestPalindromeSubsequence(string s)
{
string t = s;
reverse(t.begin(), t.end());
int n = s.size();
vector<vector<int>> dp(n + 1, vector<int>(n + 1, 0));
for (int i = 0; i <= n; i++)
{
dp[i][0] = dp[0][i] = 0;
}
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= n; j++)
{
if (s[i - 1] == t[j - 1])
{
dp[i][j] = 1 + dp[i - 1][j - 1];
}
else
{
dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
}
}
}
return dp[n][n];
}

int main()
{
string s;
cout << "Enter your string : ";
cin >> s;

cout << "Length of Longest Palindrome Subsequence is : " << longestPalindromeSubsequence(s);

return 0;
}
65 changes: 65 additions & 0 deletions sorting/heapSort.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
// C++ program for implementation of Heap Sort
#include <iostream>
using namespace std;

// To heapify a subtree rooted with node i which is
// an index in arr[]. n is size of heap
void heapify(int arr[], int n, int i)
{
int largest = i; // Initialize largest as root
int l = 2 * i + 1; // left = 2*i + 1
int r = 2 * i + 2; // right = 2*i + 2

// If left child is larger than root
if (l < n && arr[l] > arr[largest])
largest = l;

// If right child is larger than largest so far
if (r < n && arr[r] > arr[largest])
largest = r;

// If largest is not root
if (largest != i) {
swap(arr[i], arr[largest]);

// Recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}

// main function to do heap sort
void heapSort(int arr[], int n)
{
// Build heap (rearrange array)
for (int i = n / 2 - 1; i >= 0; i--)
heapify(arr, n, i);

// One by one extract an element from heap
for (int i = n - 1; i >= 0; i--) {
// Move current root to end
swap(arr[0], arr[i]);

// call max heapify on the reduced heap
heapify(arr, i, 0);
}
}

/* A utility function to print array of size n */
void printArray(int arr[], int n)
{
for (int i = 0; i < n; ++i)
cout << arr[i] << " ";
cout << "\n";
}

// Driver program
int main()
{
int arr[] = { 12, 11, 13, 5, 6, 7 };
int n = sizeof(arr) / sizeof(arr[0]);

heapSort(arr, n);

cout << "Sorted array is \n";
printArray(arr, n);
}