POJ_1984 Navigation Nightmare 【并查集】

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 
 7 using namespace std;
 8 
 9 const int MAXN = 4e4+4;
10 //X Y 表示当前节点到父节点的X， Y相对距离 
11 //DX DY 表示 输入的两个节点 X， Y相对距离
12 int X[MAXN], Y[MAXN], DX[MAXN], DY[MAXN];
13 int First[MAXN], Second[MAXN];
14 int Par[MAXN];
15 
16 void Init()
17 {
18     memset(X, 0, sizeof(X));
19     memset(Y, 0, sizeof(Y));
20     memset(Par, -1, sizeof(Par));
21 }
22 
23 int Find(int a)
24 {
25     if(Par[a] == -1)    return a;
26     int t = Par[a];
27     Par[a] = Find(Par[a]);
28     X[a] += X[t];
29     Y[a] += Y[t];
30     return Par[a];
31 }
32 
33 void Union(int a, int b, int dx, int dy)
34 {
35     int fa = Find(a);
36     int fb = Find(b);
37     if(fa != fb)
38     {
39         Par[fa] = fb;
40         X[fa] = X[b] + dx - X[a];
41         Y[fa] = Y[b] + dy - Y[a]; 
42     }
43 }
44 
45 int main()
46 {
47     //freopen("input.txt", "r", stdin);
48     int N, M, T;
49     while(scanf("%d %d", &N, &M)!=EOF)
50     {
51         Init();
52         int len;
53         char c;
54         for(int i = 0; i < M; i++)
55         {
56             scanf("%d %d %d %c", &First[i], &Second[i], &len, &c);
57             switch(c)
58             {
59                 case ‘E‘: DX[i] = len, DY[i] = 0; break;
60                 case ‘W‘: DX[i] = 0-len, DY[i] = 0; break;
61                 case ‘N‘: DX[i] = 0, DY[i] = len; break;
62                 case ‘S‘: DX[i] = 0, DY[i] = 0-len; break;
63             }
64         }
65         scanf("%d", &T);
66         int t, k = 0;
67         int u, v;
68         for(int i = 0; i < T; i++)
69         {
70             scanf("%d %d %d", &u, &v, &t);
71             for(k; k < t; k++)
72             {
73                 Union(First[k], Second[k], DX[k], DY[k]);
74             }
75             int fu = Find(u);
76             int fv = Find(v);
77             if(fu == fv)
78             {
79                 printf("%d\n", abs(X[u] - X[v]) + abs(Y[u] - Y[v]));
80             }
81             else
82             {
83                 printf("-1\n");
84             }
85             
86         }
87 
88     }
89     return 0;
90 }