UVA 10422 - Knights in FEN

链结戳我.

这是一道用BFS+Hash Table的题目。我在forum里面试了所有的test cases，都通过了，但是就是不知道为什么不能AC。眼泪掉下来T.T。

View Code 
  1 #include <iostream>
  2 #include <cstring>
  3 using namespace std;
  4 
  5 typedef int State[25];
  6 const int MAXSTATE = 1000000;
  7 const int MAXHASHSIZE = 10000000;
  8 
  9 State st[MAXSTATE],
 10     goal = {
 11     1,1,1,1,1,
 12     0,1,1,1,1,
 13     0,0,2,1,1,
 14     0,0,0,0,1,
 15     0,0,0,0,0
 16 };
 17 
 18 int dist[MAXSTATE];
 19 int head[MAXHASHSIZE], next[MAXSTATE];
 20 
 21 const int dx[] = {-2, -2, 2, 2, -1, -1, 1, 1};
 22 const int dy[] = {-1, 1, -1, 1, -2, 2, -2, 2};
 23 
 24 void init_lookup_table(){
 25     memset(head, 0, sizeof(head));
 26     memset(next, 0, sizeof(next));
 27 }
 28 
 29 int hash(State& s) {
 30     int v = 0;
 31     for (int i = 0; i < 25; i++){
 32         v += (s[i]<<i);
 33     }
 34     return v % MAXHASHSIZE;
 35 }
 36 
 37 bool try_to_insert(int s) {
 38     int h = hash(st[s]);
 39     // cout << h << endl;
 40     int u = head[h];
 41     while (u){
 42         if (memcmp(st[u], st[s], sizeof(st[s])) == 0)
 43             return false;
 44         u = next[u];
 45     }
 46     next[s] = head[h];
 47     head[h] = s;
 48     return true;
 49 }
 50 
 51 int bfs() {
 52     init_lookup_table();
 53     int front = 1, rear = 2;
 54     try_to_insert(1);
 55     while (front < rear){
 56         State& s = st[front];
 57         if (dist[front] > 10)
 58             return -1;
 59 
 60         if (memcmp(s, goal, sizeof(s)) == 0)
 61             return front;
 62 
 63         int z;
 64         for (z = 0; z < 25; z++)
 65             if (s[z] == 2)
 66                 break;
 67         int x = z/5, y = z%5;
 68         for (int i = 0; i < 8; i++){
 69             State& t = st[rear];
 70             int newx = x + dx[i],
 71                 newy = y + dy[i];
 72             int newz = newx*5 + newy;
 73             if (newx >= 0 && newx < 5 && newy >= 0 && newy < 5){
 74                 memcpy(&t, &s, sizeof(s));
 75                 t[newz] = s[z];
 76                 t[z] = s[newz];
 77                 dist[rear] = dist[front]+1;
 78                 if (try_to_insert(rear)){
 79                     rear++;
 80                 }
 81             }
 82         }
 83         front++;
 84     }
 85 }
 86 
 87 
 88 
 89 int main(int argc, char *argv[]){
 90     int cases;
 91     const int MAXLENGTH = 10;
 92     char ch[MAXLENGTH];
 93     cin.getline(ch, MAXLENGTH);
 94     cases = ch[0] - '0';
 95 
 96     while (cases--){
 97         memset(st, 0, sizeof(st));
 98         memset(dist, 0, sizeof(dist));
 99         for (int i = 0; i < 5; i++){
100             cin.getline(ch, MAXLENGTH);
101             for (int j = 0; j < 5; j++){
102                 if (ch[j] == ' ')
103                     st[1][i*5+j] = 2;
104                 else
105                     st[1][i*5+j] = ch[j] - '0';
106             }
107         }
108 
109         // cout << endl;
110         // for (int i = 0; i < 5; i++){
111         //     for (int j = 0; j < 5; j++)
112         //         cout << st[1][i*5+j];
113         //     cout << endl;
114         // }
115 
116         int ans = bfs();
117         if (ans != -1){
118             cout << "Solvable in " << dist[ans] << " move(s)." << endl;
119         }
120         else
121             cout << "Unsolvable in less than 11 move(s)." << endl;
122     }
123     return 0;
124 }

 

 

posted @ 2013-02-12 00:23  frankdj  阅读(215)  评论(0)  编辑  收藏  举报