DZY Loves Graph

按秩合并的并查集支持删边操作。

附代码

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
inline void read(int &x){
    x=0;char ch;bool flag = false;
    while(ch=getchar(),ch<'!');if(ch == '-') ch=getchar(),flag = true;
    while(x=10*x+ch-'0',ch=getchar(),ch > '!');if(flag) x=-x;
}
const int maxn = 510010;
int fa[maxn],siz[maxn];
inline int find(int x){
    while(fa[x] != x) x = fa[x];
    return x;
}
int ope[maxn];
char s[12];
struct ope{
    int op,u,v;
}op[maxn];
ll ans[maxn],sum[maxn];
int main(){
    int n,m;read(n);read(m);
    for(int i=1;i<=n;++i) fa[i] = i,siz[i] = 1;
    for(int i=1;i<=m;++i){
    scanf("%s",s);
    if(*s == 'A'){
        op[i].op = 1;
        read(op[i].u);
        read(op[i].v);
    }else if(*s == 'D'){
        op[i].op = 2;
        read(op[i].u);
    }else if(*s == 'R') op[i].op = 3;
    }
    int ecnt = 0,nodecnt = n;
    for(int i=1;i<=m;++i){
    if(op[i].op == 1){
        if(op[i+1].op == 3){
        if(nodecnt == 1) printf("%lld\n",ans[ecnt]);
        else if(nodecnt == 2){
            int x = find(op[i].u);
            int y = find(op[i].v);
            if(x == y) puts("0");
            else printf("%lld\n",sum[ecnt] + i);
        }else puts("0");
        printf("%lld\n",ans[ecnt]);
        ++ i;
        }else{
        ans[ecnt+1] = ans[ecnt];
        sum[ecnt+1] = sum[ecnt];
        ++ecnt;
        int x = find(op[i].u);
        int y = find(op[i].v);
        if(x == y){
            printf("%lld\n",ans[ecnt]);
            ope[ecnt] = 0;
            continue;
        }
        if(siz[x] > siz[y]) swap(x,y);
        fa[x] = y;siz[y] += siz[x];ope[ecnt] = x;
        sum[ecnt] += i;
        if(--nodecnt == 1) ans[ecnt] = sum[ecnt];
        printf("%lld\n",ans[ecnt]);
        }
    }else if(op[i].op == 2){
        if(op[i+1].op == 3){
        printf("%lld\n",ans[ecnt-op[i].u]);
        ++ i;
        printf("%lld\n",ans[ecnt]);
        }else{
            for(int j=0;j<op[i].u;++j){
            if(ope[ecnt] != 0){
            int x = ope[ecnt];
            ++ nodecnt;
            siz[fa[x]] -= siz[x];
            fa[x] = x;
            }-- ecnt;
        }
        printf("%lld\n",ans[ecnt]);
        }
    }
    }
    return 0;
}