首先bfs， 求出两两之间的距离， 然后dfs就可以。
1 #include <iostream> 2 #include <cstdio> 3 #include <algorithm> 4 #include <cstring> 5 #include <cmath> 6 #include <string> 7 #include <queue> 8 #include <vector> 9 #include <map> 10 #include <set> 11 using namespace std; 12 #define pb(x) push_back(x) 13 #define ll long long 14 #define mk(x, y) make_pair(x, y) 15 #define mem(a) memset(a, 0, sizeof(a)) 16 #define lson l, m, rt<<1 17 #define rson m+1, r, rt<<1|1 18 #define mem1(a) memset(a, -1, sizeof(a)) 19 #define mem2(a) memset(a, 0x3f, sizeof(a)) 20 #define rep(i, a, n) for(int i = a; i<n; i++) 21 #define ull unsigned long long 22 typedef pair<int, int> pll; 23 const double PI = acos(-1.0); 24 const int inf = 1061109567; 25 const double eps = 1e-8; 26 const int mod = 1e9+7; 27 const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} }; 28 char c[30][30]; 29 int dis[15][15], vis[30][30], n, m, cnt, ans, used[20]; 30 struct node 31 { 32 int x, y, step; 33 node(){} 34 node(int x, int y, int step):x(x), y(y), step(step){} 35 }; 36 int bfs(pll s, pll e) { 37 mem(vis); 38 vis[s.first][s.second] = 1; 39 queue <node> q; 40 q.push(node(s.first, s.second, 0)); 41 while(!q.empty()) { 42 node tmp = q.front(); q.pop(); 43 if(tmp.x == e.first && tmp.y == e.second) 44 return tmp.step; 45 for(int i = 0; i<4; i++) { 46 int tmpx = tmp.x + dir[i][0]; 47 int tmpy = tmp.y + dir[i][1]; 48 if(tmpx>=0&&tmpx<n&&tmpy>=0&&tmpy<m&&!vis[tmpx][tmpy]&&c[tmpx][tmpy]!='x') { 49 q.push(node(tmpx, tmpy, tmp.step+1)); 50 vis[tmpx][tmpy] = 1; 51 } 52 } 53 } 54 return 0; 55 } 56 void dfs(int now, int num, int now_dis) { 57 if(now_dis>=ans) 58 return ; 59 if(num == cnt-1) { 60 if(now_dis<ans) { 61 ans = now_dis; 62 } 63 return ; 64 } 65 for(int i = 1; i<cnt; i++) { 66 if(!used[i]) { 67 used[i] = 1; 68 dfs(i, num+1, now_dis+dis[now][i]); 69 used[i] = 0; 70 } 71 } 72 } 73 pll point[20]; 74 int main() 75 { 76 while(scanf("%d%d", &m, &n)) { 77 if(n+m==0) 78 break; 79 int sx, sy; 80 mem(dis); 81 cnt = 1; 82 for(int i = 0; i<n; i++) 83 scanf("%s", c[i]); 84 for(int i = 0; i<n; i++) { 85 for(int j = 0; j<m; j++) { 86 if(c[i][j] == 'o') { 87 c[i][j] = '0'; 88 point[0].first = i; 89 point[0].second = j; 90 } 91 if(c[i][j] == '*') { 92 point[cnt].first = i; 93 point[cnt++].second = j; 94 } 95 } 96 } 97 for(int i = 0; i<cnt; i++) { 98 for(int j = i+1; j<cnt; j++) { 99 dis[i][j] = dis[j][i] = bfs(point[i], point[j]); 100 } 101 } 102 int flag = 0; 103 for(int i = 1; i<cnt; i++) { 104 if(dis[0][i] == 0) { 105 flag = 1; 106 } 107 } 108 if(flag) { 109 puts("-1"); 110 continue; 111 } 112 mem(used); 113 used[0] = 1; 114 ans = inf; 115 dfs(0, 0, 0); 116 printf("%d ", ans); 117 } 118 }