Connections in Galaxy War ZOJ - 3261

离线维护,逆序处理

#include<cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <map>
using namespace std;
#define fst first
#define sec second
#define sci(num) scanf("%d",&num)
#define scl(num) scanf("%lld",&num)
#define mem(a,b) memset(a,b,sizeof a)
#define cpy(a,b) memcopy(a,b,sizeof b)
typedef long long LL;
typedef pair<int,int> P;
const int MAX_N = 10010;
const int MAX_M = 20010;
int Fa[MAX_N],W[MAX_N],N,M;
P es[MAX_M];
bool vis[MAX_M];
map<P,int> ids;
struct Que{
    int f,s,e;
} query[50010];
int ans[50010],cnt;
void init() {
    mem(vis,0);
    ids.clear();
    for (int i =0;i <= N;i++) {
        Fa[i] = i;
    }
    cnt = 0;
}
int Find(int x) {
    if (Fa[x] != x) {
        Fa[x] = Find(Fa[x]);
    }
    return Fa[x];
}
void Union(int x,int y) {
    x = Find(x);
    y = Find(y);
    if (x == y) return;
    if (W[x] > W[y]) {
        Fa[y] = x;
    } else if (W[x] < W[y]){
        Fa[x] = y;
    } else if (x < y) {
        Fa[y] = x;
    } else {
        Fa[x] = y;
    }
}
int main() {
    int f = 0;
    while (~sci(N)) {
        for (int i = 0;i < N;i++)
            sci(W[i]);
        init();
        if (f++) printf("\n");
        sci(M);
        for (int i =0 ;i < M;i++) {
            sci(es[i].fst); sci(es[i].sec);
            if (es[i].fst > es[i].sec) {
                swap(es[i].fst,es[i].sec);
            }
            ids[es[i]] = i;
        }
        int Q;
        sci(Q);
        for (int i = 0;i < Q;i++) {
            
   
    char
    str[10];
            scanf("%s",str);
            if (str[0] == 'q') {
                query[i].f = 0;
                sci(query[i].s);
            } else {
                query[i].f = 1;
                sci(query[i].s);
                sci(query[i].e);
                if (query[i].s > query[i].e) {
                    swap(query[i].s,query[i].e);
                }
                vis[ids[make_pair(query[i].s,query[i].e)]] = true;
            }
        }
        for (int i = 0;i < M;i++) {
            if (!vis[i]) Union(es[i].first,es[i].second);
        }
        for (int i = Q - 1;i >= 0;i--) {
            if (query[i].f == 0) {
                int t = Find(query[i].s);
                ans[cnt++] = W[Fa[query[i].s]] > W[query[i].s] ? t : -1;
            } else {
                int id = ids[make_pair(query[i].s,query[i].e)];
                Union(es[id].first,es[id].second);
            }
        }
        for (int i = cnt - 1;i>= 0;i--) {
            printf("%d\n",ans[i]);
        }
    }

    return 0;
}