NTL_1_B | Power

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AOJ

Table of contents

# Problem

http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=NTL_1_B

Given X and N, report the power N of X.

# Time complexity

O(log⁡N)O(\log N)

# Solution

// C++ 14
#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <math.h>

#define ll long long
#define Int int
#define loop(x, start, end) for(Int x = start; x < end; x++)
#define loopdown(x, start, end) for(int x = start; x > end; x--)
#define rep(n) for(int x = 0; x < n; x++)
#define span(a,x,y) a.begin()+x,a.begin()+y
#define span_all(a) a.begin(),a.end()
#define len(x) (x.size())
#define last(x) (*(x.end()-1))

using namespace std;
#define M 1000000007

Int X, Y;

Int faster_pow(Int x, Int y) {
  if (y == 0) return 1;
  Int res = faster_pow((x * x) % M, y / 2);
  if (y % 2 == 1) {
    res = (res * x) % M;
  }
  return res;
}

void input() {
  cin >> X >> Y;
}

void solve() {
  cout << faster_pow(X, Y) << endl;
}

int main() {
  input();
  solve();
  return 0;
}

Shun

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