快速冪

快速計算a^b

防止超時

#include <bits/stdc++.h>

using namespace std;
long long powmod(int a, int b);
int main()
{
    int a, b;
    cin >> a >> b;
    cout << powmod(a, b) << endl;
    return 0;
}
long long powmod(int a, int b)
{
    long long  cases, k;
    cases = 1;
    k = a;
    while(b > 0)
    {
    if(b%2) cases *= k;
    k *= k;
    b /= 2;
    }
    return cases;
}