Network Saboteur(dfs)
http://poj.org/problem?id=2531
不太理解这个代码。。。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <stdio.h> 2 #include <string.h> 3 int map[32][32],v[32]; 4 int n,max; 5 void dfs(int row,int sum) 6 { 7 8 int ans = sum; 9 v[row] = 1; 10 for (int i = 1; i <= n; i ++) 11 { 12 if (v[i]==0) 13 ans += map[row][i]; 14 else 15 ans -= map[row][i]; 16 } 17 if (ans > max) 18 max = ans; 19 for (int i = row+1; i <= n; i ++) 20 { 21 if (ans > sum) 22 { 23 dfs(i,ans); 24 v[i] = 0; 25 } 26 } 27 } 28 int main() 29 { 30 scanf("%d",&n); 31 max = 0; 32 memset(v,0,sizeof(v)); 33 for (int i = 1; i <= n; i ++) 34 { 35 for (int j = 1; j <= n; j ++) 36 { 37 scanf("%d",&map[i][j]); 38 } 39 } 40 dfs(1,0); 41 printf("%d\n",max); 42 return 0; 43 44 }