(재귀)1629 곱셈/1074 Z

1.1629 곱셈

https://www.acmicpc.net/problem/1629

1629번: 곱셈

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

using ll = long long;

ll POW(ll a, ll b, ll c) {
    if (b == 1) return a % c;
    ll value = POW(a, b / 2, c);
    value = value * value % c;
    if (b % 2 == 0) return value;
    return value * a % c;
    
}
int main() {
    cin.tie(NULL);
    cin.sync_with_stdio(false);
    cout.tie(NULL);

    ll a, b, c;
    cin >> a >> b >> c;
    cout << POW(a, b, c);
    
}

 

2.1074 Z

https://www.acmicpc.net/problem/1074

1074번: Z

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
int function1(int n, int r, int c) {
    if (n == 0) return 0;
    int half = 1 << (n - 1);//1을 왼쪽으로 n-1번 이동, half=2^(n-1)
    if (r < half && c < half) return function1(n - 1, r, c);
    if (r < half && c >= half) return half*half+ function1(n - 1, r, c - half);
    if (r >= half && c < half)return 2 * half * half + function1(n - 1, r - half, c);
    return 3 * half * half + function1(n - 1, r - half, c - half);

}
int main() {
    cin.tie(NULL);
    cin.sync_with_stdio(false);
    cout.tie(NULL);

    int n, r, c;
    cin >> n >> r >> c;
    cout << function1(n, r, c);
    
}