UVA 11859 - Division Game(Nim游戏)

UVA 11859 - Division Game

题目链接

题意：给定一个矩阵，每次能选一行中几个数字，把他们变成他们的因子，最后不能变的人输，问是否能先手必胜

思路：转变成因子等价于删去一些素数，这样问题转化为了Nim游戏

代码：

#include <stdio.h>#include <string.h>const int N = 10005;int t, n, m, num, cnt[N], vis[N], prime[N], pn = 0;int main() {for (int i = 2; i < N; i++) {if (vis[i]) continue;prime[pn++] = i;for (int j = i; j < N; j += i) {vis[j] = 1;  } } for (int i = 2; i < N; i++) { int num = i;   for (int j = 0; j < pn && prime[j] <= i; j++) { while (num % prime[j] == 0) { cnt[i]++; num /= prime[j]; }   }  } int cas = 0;scanf("%d", &t);while (t--) {int ans = 0;scanf("%d%d", &n, &m);for (int i = 0; i < n; i++) {int sum = 0;   for (int j = 0; j < m; j++) {   scanf("%d", &num);sum += cnt[num];   }   ans ^= sum;  }  printf("Case #%d: %s\n", ++cas, ans == 0?"NO":"YES"); }return 0;}