描述：采用双广搜完成，因为单广搜层数太多，不但超时（结果根本出不来），而且还超内存（开不下这么大的数组），双广搜分为两部分，每部分的层数都为8层，分别是从开始的转轮和最终的转轮开始广搜，遇到重合了就可以输出路径，如果不重合，顶多两部分全都搜完，由于目标转轮是确定的，所以第一次的从目标转轮进行的广搜可以存储下来，以后只需要从开始的转轮广搜就可以了，这样可以节省时间。#include <stdio.h>#include <string.h>#define MAX 200000#define HASHSIZE 10000003struct way{ int step; int l; int len; int s[21];};int head[2][HASHSIZE], next[2][MAX];int a[24];int front, rear,mid, flag;int target[21] = {0, 3, 4, 3, 0, 5, 6, 5, 0, 1, 2, 1, 0, 7, 8, 7, 0, 9, 10, 9, 0};way v[MAX];int hash(int *p){ int c = 0; for (int i = 0; i < 21; i++) c = (c * 10 + p[i]) % HASHSIZE; return c;}int insert(int t, int cur){ int h = hash(v[t].s); int u = head[cur][h]; while(u != -1) { if (memcmp(v[t].s, v[u].s, sizeof(v[t].s)) == 0) return 0; u = next[cur][u]; } next[cur][t] = head[cur][h]; head[cur][h] = t; return 1;}int search(int pos){ int h = hash(v[pos].s); int u = head[1][h]; while (u != -1) { if (memcmp(v[u].s, v[pos].s, sizeof(v[pos].s)) == 0) return u; u = next[1][u]; } return -1;}void show1(int pos){ if (v[pos].l == -1) return; show1(v[pos].l); printf("%d", v[pos].len);}void show2(int pos){ if (v[pos].l == -1) return; if(v[pos].len>2) printf("%d", v[pos].len-2 ); else printf("%d", v[pos].len +2); show2(v[pos].l);}void bfs(int cur){ way tmpway, newway; memcpy(v[front].s, a, sizeof(v[front].s)); v[front].l = -1; v[front].step = v[front].len = 0; insert(front, cur); while (front < rear) { tmpway = v[front]; if (!cur && (mid = search(front)) != -1) { show1(front); show2(mid); printf("\n"); flag=1; return; } if (tmpway.step <8) for(int i=1; i<=4; i++) { newway = tmpway; newway.l = front; newway.step++; newway.len = i; int temp1, temp2; if(i==1) { temp1 = newway.s[10]; temp2 = newway.s[11]; for (int i = 9; i >= 0; i--) newway.s[i + 2] = newway.s[i]; newway.s[0] = temp1; newway.s[1] = temp2; } else if(i==2) { temp1 = newway.s[9]; temp2 = newway.s[10]; for (int i = 9; i < 19; i++) newway.s[i] = newway.s[i + 2]; newway.s[20] = temp2; newway.s[19] = temp1; } else if(i==3) { temp1 = newway.s[0]; temp2 = newway.s[1]; for (int i = 2; i < 12; i++) newway.s[i - 2] = newway.s[i]; newway.s[10] = temp1; newway.s[11] = temp2; } else { temp1 = newway.s[19]; temp2 = newway.s[20]; for (int i = 18; i >= 9; i--) newway.s[i + 2] = newway.s[i]; newway.s[9] = temp1; newway.s[10] = temp2; } v[rear] = newway; if (insert(rear, cur)) rear++; } front++; }}int main(){ int n;#ifndef ONLINE_JUDGE freopen("a.txt", "r", stdin);#endif scanf("%d", &n); memset(head, -1, sizeof(head)); memset(next,0,sizeof(next)); front =0; rear = 1; memcpy(a, target, sizeof(target)); bfs(1); int score1=front,score2=rear; while (n--) { for (int i = 0; i < 24; i++) scanf("%d", &a[i]); memset(head[0], -1, sizeof(head[0])); memset(next[0],0,sizeof(next[0])); if(memcmp(a,target,sizeof(target))==0) printf("PUZZLE ALREADY SOLVED\n"); else { front=score1; rear=score2+1; flag=0; bfs(0); if(!flag) printf("NO SOLUTION WAS FOUND IN 16 STEPS\n"); } } return 0;}
