Adding Solution for 237-C Codeforces

C++/All Sieve Functions.txt

@@ -0,0 +1,102 @@
+bool Not_prime[N]={};
+bool IsPrime(int n)
+{
+    if (n==2)
+        return true;
+    if (n<2||n%2==0)
+        return false;
+    for (int i=3; i*i<=n; i+=2)
+        if (n%i==0)
+            return false;
+    return true;
+}
+vector<ll>divisors;
+void Divs(ll n)
+{
+    for (ll i=1; i*i<=n; ++i)
+    {
+        if (n%i==0)
+        {
+            divisors.push_back(i);
+            if (!(i*i==n))
+                divisors.push_back(n/i);
+        }
+    }
+}
+ll NoofDivisors(ll n)
+{
+    ll cnt=1;
+    for (ll i=2; i*i<=n; ++i)
+    {
+        int power=0;
+        while (n%i==0)
+        {
+            n/=i;
+            ++power;
+        }
+        cnt*=(power+1);
+    }
+    if (n>1)
+        cnt*=2;
+    return cnt;
+}
+int number_of_divisors[N]= {};
+void Sieve_NoofDivisors(int n)
+{
+    number_of_divisors[0]=number_of_divisors[1]=1;
+    for (int i=2; i*i<=n; ++i)
+        if (!number_of_divisors[i])
+            for (int j=i; j<n; j+=i)
+            {
+                int e=0;
+                int q=j;
+                while (q%i==0)
+                {
+                    ++e;
+                    q/=i;
+                }
+                if(number_of_divisors[j])
+                    number_of_divisors[j]*=(e+1);
+                else
+                    number_of_divisors[j]=(e+1);
+            }
+}
+vector<int> primes;
+void prime_fact(ll n)
+{
+    bool ok=false;
+    for(ll i = 2 ; i * i <= n ; i++)
+    {
+        while(n % i == 0)
+        {
+            ok=1;
+            n /= i;
+        }
+        if(ok)
+        primes.push_back(i);
+        ok=0;
+    }
+    if(n > 1)
+        primes.push_back(n);
+}
+void Sieve()
+{
+    Not_prime[0]=Not_prime[1]=true;
+    for (ll i=2; i*i<=N; ++i)
+        if (!Not_prime[i])
+            for (ll j=i*i; j<=N; j+=i)
+                Not_prime[j]=true;
+}
+int cntPrime[N];
+void seive()
+{
+    for(ll i=2; i<N; i++)
+    {
+        if(cntPrime[i])
+            continue;
+        for(ll j=i; j<N; j+=i)
+        {
+            cntPrime[j]++;
+        }
+    }
+}

C++/Primes on Interval-237-C.cpp

@@ -0,0 +1,56 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int N = 1e6 + 5;
+
+typedef long long ll;
+
+int a, b, k;
+int cntPrimes[N];
+bool notPrime[N];
+
+void seive()
+{
+	notPrime[0] = notPrime[1] = true;
+	for(ll i = 2; i < N; i++)
+	{
+		if(notPrime[i]) continue;
+		for(ll j = i * i; j < N; j += i)
+		{
+			notPrime[j] = true;
+		}
+	}
+	for(int i = 2; i < N; i++)
+	{
+		cntPrimes[i] += cntPrimes[i - 1] + (!notPrime[i]);
+	}
+}
+
+bool valid(int l)
+{
+	for(int i = a; i + l - 1 <= b; i++)
+	{
+		if(cntPrimes[i + l - 1] - cntPrimes[i - 1] < k) return false;
+	}
+	return true;
+}
+
+int main()
+{
+	seive();
+	scanf("%d%d%d", &a, &b, &k);
+	int s = 1, e = b - a + 1, mid, l = -1;
+	while(s <= e)
+	{
+		mid = s + (e - s) / 2;
+		if(valid(mid))
+		{
+			l = mid;
+			e = mid - 1;
+		}
+		else s = mid + 1;
+	}
+	printf("%d\n", l);
+	return 0;
+}