python/TangDou/LuoGuBook/P1161.cpp

#include<bits/stdc++.h>

using namespace std;
const int N = 2000010;
int b[N];   //灯的状态
double a;   //1-1000的实数
int n;      //操作数量
int t;      //倍数

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a >> t;
        for (int j = 1; j <= t; j++) {
            int x = a * j;
            b[x] = !b[x];
        }
    }
    for (int i = 1; i < N; i++)
        if (b[i]) {
            printf("%d ", i);
            break;
        }
    return 0;
}