Ural 1671. Anansi's Cobweb（并查集）

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题目链接：点击打开链接

思路：

由于我们对删除边之后的状态很难处理，我们可以考虑对询问倒着处理，转化成对集合的合并问题。

细节参见代码：

#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>#include <string>#include <vector>#include <stack>#include <ctime>#include <bitset>#include <cstdlib>#include <cmath>#include <set>#include <list>#include <deque>#include <map>#include <queue>#define Max(a,b) ((a)>(b)?(a):(b))#define Min(a,b) ((a)<(b)?(a):(b))using namespace std;typedef long long ll;typedef long double ld;const double eps = 1e-6;const double PI = acos(-1);const int mod = 1000000000 + 7;const int INF = 0x3f3f3f3f;const int maxn = 1e5 + 10;int T,n,m,q,p[maxn],vis[maxn],u[maxn],v[maxn],op[maxn];int _find(int x) { return p[x] == x ? x : p[x] = _find(p[x]); }int main() {    while(~scanf("%d%d",&n, &m)) {        for(int i = 1; i <= m; i++) {            scanf("%d%d", &u[i], &v[i]);            vis[i] = 0;        }        scanf("%d", &q);        for(int i = 1; i <= q; i++) {            scanf("%d", &op[i]);            vis[op[i]] = 1;        }        for(int i = 1; i <= n; i++) p[i] = i;        int ans = n;        for(int i = 1; i <= m; i++) {            if(vis[i]) continue;            int x = _find(u[i]);            int y = _find(v[i]);            if(x != y) p[x] = y, --ans;        }        vector<int> res;        for(int i = q; i >= 1; i--) {            res.push_back(ans);            int id = op[i];            int x = _find(u[id]);            int y = _find(v[id]);            if(x != y) {                p[x] = y;                --ans;            }        }        for(int i = q-1; i >= 0; i--) {            printf("%d%c", res[i], i == 0 ? '\n' : ' ');        }    }    return 0;}

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