Navigation Nightmare POJ - 1984

版权声明： https://blog.csdn.net/weixin_40959045/article/details/88382165

维护东西南北的差值，相当于维护两个并查集

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

#define MAX_N 50010

#define sci(num) scanf("%d",&num)
#define mem(a,b) memset(a,b,sizeof a)
using namespace std;
#define  MOD 3
int fa[MAX_N], rx[MAX_N],ry[MAX_N];
int N,M,K;
struct que{
    int x,y,d;
    
    
    
     
     char
    
     ch;
} qs[40010];
int Find(int x) {
    if (fa[x] != x) {
        int p = fa[x];
        fa[x] = Find(fa[x]);
        rx[x] += rx[p];
        ry[x] += ry[p];
    }
    return fa[x];
}
void init() {
    for (int i = 0;i <= N;i++) {
        fa[i] = i;
        rx[i] = ry[i] = 0;
    }
}
void Union(int x,int y,int d,
    
    
     
     char
    
     ch) {

    int fx = Find(x);
    int fy = Find(y);
    if (ch == 'E' || ch == 'W') {
        if (fx != fy) {
            rx[fy] = rx[x] - (d + rx[y]);
            ry[fy] = ry[x] - ( ry[y]);
            fa[fy] = fx;
        }
    } else if (ch == 'N' || ch == 'S') {
        if (fx != fy) {
            rx[fy] = rx[x] - ( rx[y]);
            ry[fy] = ry[x] - ( d + ry[y]);
            fa[fy] = fx;
        }
    }
}
int main() {
    sci(N); sci(M);
    init();
    for (int i = 0;i < M;i++) {
        scanf("%d %d %d %c\n",&qs[i].x,&qs[i].y,&qs[i].d,&qs[i].ch);
        if (qs[i].ch == 'W') qs[i].d= -qs[i].d;
        if (qs[i].ch == 'S') qs[i].d = -qs[i].d;
    }
    int now = 0;
    sci(K);
    for (int i = 0;i < K;i++) {
        int x,y,w;
        sci(x); sci(y); sci(w);
        for (;now < w;now++) {
            Union(qs[now].x,qs[now].y,qs[now].d,qs[now].ch);
        }
        int fx = Find(x);
        int fy = Find(y);
        if (fx != fy) {
            printf("-1\n");
        } else {
            printf("%d\n",abs(rx[x] - rx[y]) + abs(ry[x] - ry[y]));
        }
    }

    return 0;
}