[POJ1611]The Suspects（并查集）

传送门

通过并查集统计集合个数，easy

——代码

#include <cstdio>
#include <iostream>
#define N 1000001

int n, m;
int f[N], num[N];

inline int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;
    for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';
    return x * f;
}

inline int find(int x)
{
    return x == f[x] ? x : f[x] = find(f[x]);
}

inline void connect(int x, int y)
{
    x = find(x);
    y = find(y);
    if(x ^ y) f[x] = y, num[y] += num[x];
}

int main()
{
    int i, j, k, x, y;
    while(~scanf("%d %d", &n, &m))
    {
        if(!n && !m) break;
        for(i = 0; i <= n; i++) f[i] = i, num[i] = 1;
        for(i = 1; i <= m; i++)
        {
            k = read();
            if(k) y = read();
            for(j = 2; j <= k; j++)
            {
                x = read();
                connect(x, y);
                y = x;
            }
        }
        printf("%d
", num[find(0)]);
    }
    return 0;
}