Ural_1671. Anansi's Cobweb(并查集)

　　/*思路参考大牛，我脑袋被lv踢了，居然想到用数状数组写。。。
思路：并查集，先把不许要删的边用并查集合并，然后把需要删的边逆序加入到并查集中。。。。

My Code：*/

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int N = 100005;

struct node {
    int s;
    int e;
}g[N];

int parent[N];
int c[N];
int ans[N];
int Rank[N];
bool vis[N];

void init(int n) {
    for(int i = 1; i <= n; i++) {
        parent[i] = i;
        Rank[i] = 0;
        vis[i] = false;
    }
}

int find(int x) {
    int k, r, j;
    r = x; k = x;
    while(r != parent[r]) {
        r = parent[r];
    }
    while(k != r) {
        j = parent[k];
        parent[k] = r;
        k = j;
    }
    return r;
}

void union_set(int x, int y) {
    x = find(x);
    y = find(y);
    if(x == y)    return;
    if(Rank[x] > Rank[y])    parent[y] = x;
    else {
        parent[x] = y;
        if(Rank[x] == Rank[y])    ++ Rank[y];
    }
}

int main() {
    //freopen("data.in", "r", stdin);

    int n, m, i, k, cnt;
    while(~scanf("%d%d", &n, &m)) {
        init(n); cnt = 0;
        for(i = 1; i <= m; i++) {
            scanf("%d%d", &g[i].s, &g[i].e);
            vis[i] = true;
        }
        
        scanf("%d", &k);
        for(i = 0; i < k; i++) {
            scanf("%d", &c[i]);
            vis[c[i]] = false;
        }
        
        for(i = 1; i <= m; i++) {
            if(!vis[i])    continue;
            if(find(g[i].s) != find(g[i].e)) {
                union_set(g[i].s, g[i].e);
                cnt++;
            }
        }
        
        for(i = k-1; i >= 0; i--) {
            ans[i] = n-cnt;
            if(find(g[c[i]].s) != find(g[c[i]].e)) {
                union_set(g[c[i]].s, g[c[i]].e);
                cnt++;
            }
        }
        
        for(i = 0; i < k; i++) {
            printf("%d", ans[i]);
            if(i == k-1)    putchar('\n');
            else    putchar('');
        }
    }
    return 0;
}