POJ

来源：互联网发布：喝咖啡的利弊知乎编辑：程序博客网时间：2024/04/30 08:45

思路：求与0连通的学生数，包含0自身。

AC代码：

#include <cstdio>#include <cmath>#include <cctype>#include <algorithm>#include <cstring>#include <utility>#include <string>#include <iostream>#include <map>#include <set>#include <vector>#include <queue>#include <stack>using namespace std;#pragma comment(linker, "/STACK:1024000000,1024000000") #define eps 1e-10#define inf 0x3f3f3f3f#define PI pair<int, int> typedef long long LL;const int maxn = 30000 + 5;int p[maxn];int find(int x) {return p[x] == x ? x : p[x] = find(p[x]);}void join(int x, int y) {int px = find(x), py = find(y);if(px != py) p[px] = py;}int main() {int n, m;while(scanf("%d%d", &n, &m) == 2 && n+m) {for(int i = 0; i < n; ++i) p[i] = i;int num, x, y;for(int i = 0; i < m; ++i) {scanf("%d%d", &num, &x);for(int j = 1; j < num; ++j) {scanf("%d", &y);join(x, y);x = y;}}int goal = find(0);int ans = 0;for(int i = 0; i < n; ++i) {if(find(i) == goal) ++ans;}printf("%d\n", ans);}return 0;}

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