HDU 4496

思路：并查集应用，处理是倒过来处理。

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std; 
int father[10005], a[100005], b[100005], block[100005]; 
int find(int x)
{
    return x == father[x] ? x : father[x] = find(father[x]); 
}

void unit(int x, int y)
{
    int a = find(x); 
    int b = find(y); 
    father[a] = father[b]; 
    return ; 
}

int main(int argc, char const *argv[]) 
{
    int n, m; 
    //freopen("in.c", "r", stdin); 
    while(~scanf("%d%d", &n, &m))
    {
        memset(block, 0, sizeof(block)); 
        for(int i = 0;  i < n; i ++)
            father[i] = i; 
        for(int i = 0; i < m; i ++)
            scanf("%d%d", &a[i], &b[i]);  
        for(int i = m-1; i >= 0; i --)
        {
            block[i] = n; 
            if(find(a[i]) != find(b[i]))
            {
                n--; 
                unit(a[i], b[i]); 
            }
        }
        for(int i = 0;i < m; i ++)
            printf("%d\n", block[i]);
    }
    return 0; 
}