USACO3.25Magic Squares（bfs）
1 /* 2 ID: shangca2 3 LANG: C++ 4 TASK: msquare 5 */ 6 #include <iostream> 7 #include<cstdio> 8 #include<cstring> 9 #include<algorithm> 10 #include<stdlib.h> 11 #include<queue> 12 #define INF 0xfffffff 13 using namespace std; 14 int o[10]; 15 typedef struct node 16 { 17 int num; 18 int a[10],pre; 19 char c; 20 }st; 21 st q[50000],ss; 22 char s1[10010],s2[10010]; 23 int f[8][8][8][8][8][8][8]; 24 void bfs() 25 { 26 int i,d=1,p=0,minz = INF; 27 q[d].num = 0; 28 q[d].pre = -1; 29 for(i = 1; i <= 8 ; i++) 30 q[d].a[i] = i; 31 f[0][1][2][3][4][5][6] = 1; 32 while(p!=d) 33 { 34 p++; 35 ss = q[p]; 36 if(ss.num>minz) 37 continue; 38 for(i = 1; i <= 8 ; i++) 39 { 40 if(ss.a[i]!=o[i]) 41 break; 42 } 43 if(i==9) 44 { 45 int x = ss.pre,w=0; 46 s2[w++] = ss.c; 47 while(x!=-1) 48 { 49 s2[w++] = q[x].c; 50 x = q[x].pre; 51 } 52 s2[w] = '\0'; 53 if(ss.num<minz) 54 { 55 minz = ss.num; 56 strcpy(s1,s2); 57 } 58 else 59 { 60 if(strcmp(s2,s1)>0) 61 strcpy(s1,s2); 62 } 63 continue; 64 } 65 int b[10]; 66 for(i = 8; i >= 1 ; i--) 67 b[i] = ss.a[8-i+1]; 68 if(!f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1]) 69 { 70 d++; 71 q[d].num = ss.num+1; 72 q[d].c = 'A'; 73 q[d].pre = p; 74 f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1] = 1; 75 for(i = 1; i <= 8 ; i++) 76 q[d].a[i] = b[i]; 77 } 78 for(i = 1; i <= 8 ; i++) 79 { 80 if(i>1&&i<=4) 81 b[i] = ss.a[i-1]; 82 if(i==1) 83 b[i] = ss.a[4]; 84 if(i==8) 85 b[i] = ss.a[5]; 86 if(i>4&&i<8) 87 b[i] = ss.a[i+1]; 88 } 89 if(!f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1]) 90 { 91 d++; 92 q[d].num = ss.num+1; 93 q[d].c = 'B'; 94 q[d].pre = p; 95 f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1] = 1; 96 for(i = 1; i <= 8 ; i++) 97 q[d].a[i] = b[i]; 98 } 99 for(i = 1; i <= 8 ; i++) 100 { 101 if(i==2) 102 b[i] = ss.a[7]; 103 else if(i==3) 104 b[i] = ss.a[2]; 105 else if(i==6) 106 b[i] = ss.a[3]; 107 else if(i==7) 108 b[i] = ss.a[6]; 109 else b[i] = ss.a[i]; 110 } 111 if(!f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1]) 112 { 113 d++; 114 q[d].num = ss.num+1; 115 q[d].c = 'C'; 116 q[d].pre = p; 117 f[b[1]-1][b[2]-1][b[3]-1][b[4]-1][b[5]-1][b[6]-1][b[7]-1] = 1; 118 for(i = 1; i <= 8 ; i++) 119 q[d].a[i] = b[i]; 120 } 121 } 122 printf("%d\n",minz); 123 if(minz!=0) 124 { 125 int k = strlen(s1),qq=0; 126 for(i = k-1 ; i>= 0; i--) 127 { 128 qq++; 129 cout<<s1[i]; 130 if(qq%60==0||i==0) 131 puts(""); 132 } 133 } 134 else 135 puts(""); 136 } 137 int main() 138 { 139 freopen("msquare.in","r",stdin); 140 freopen("msquare.out","w",stdout); 141 int i; 142 for(i =1; i <= 8 ; i++) 143 cin>>o[i]; 144 bfs(); 145 return 0; 146 }
这题 亮点在于开了个7维数组。。。