题目大意就是 你有足够多的坦克，让你用尽量多的坦克去占领电厂。有N+1各节点，0~n ，0为出发点，1~n为电厂。要想控制摧毁电厂，战胜对方，只需要占领一般的电量即可。但是特克会耗油，所一给你m条路，让你去计算最小耗电量~而且如果坦克不能通过m条路到达任意一个电厂的话就输出'impossible'
连接：http://acm.hdu.edu.cn/showproblem.php?pid=3339
代码：dij
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1 #include <stdio.h> 2 #include <string.h> 3 #define maxn 0x5fffffff 4 int map[105][105]; 5 int dis[105]; 6 void inint(int n) 7 { 8 int j,i; 9 for(i = 0;i <= n;i++) 10 { 11 for(j = 0;j <= n;j++) 12 if(i != j)map[i][j] = maxn; 13 else map[i][j] = 0; 14 } 15 } 16 void disj(int n) 17 { 18 int vis[105] = {0}; 19 int pre,i,j,k,min; 20 pre = 0; 21 for(i = 0;i <= n;i++) 22 dis[i] = map[pre][i]; 23 vis[pre] = 1; 24 25 for(k = 1;k <= n;k++) 26 { 27 for(i = 0;i <= n;i++) 28 { 29 if(!vis[i] && dis[i] > dis[pre]+map[pre][i]) 30 dis[i] = dis[pre]+map[pre][i]; 31 } 32 min = maxn; 33 for(i = 0;i <= n;i++) 34 if(min > dis[i] && !vis[i]) 35 min = dis[i],pre = i; 36 37 vis[pre] = 1; 38 } 39 } 40 int main() 41 { 42 int T,n,m,i,j,a,b,c,sum,pow[105],spow,f[20005]; 43 scanf("%d",&T); 44 while(T--) 45 { 46 scanf("%d %d",&n,&m); 47 inint(n); 48 for(i = 0;i < m;i++) 49 { 50 scanf("%d%d%d",&a,&b,&c); 51 if(c < map[a][b]) 52 map[a][b] = map[b][a] = c; 53 } 54 55 disj(n); 56 spow = sum = 0; 57 for(i = 1;i <= n;i++) 58 scanf("%d",pow+i),spow+=pow[i]; 59 int leap = 0; 60 for(i = 1;i <= n;i++) 61 { 62 if(dis[i] != maxn) 63 sum += dis[i]; 64 else 65 leap = 1; 66 } 67 if(leap) 68 puts("impossible"); 69 else 70 { 71 memset(f,0,sizeof(f)); 72 for(i = 1;i <= n;i++) 73 { 74 for(j = sum;j >= dis[i];j--) 75 { 76 if(f[j] < f[j-dis[i]]+pow[i]) 77 f[j] = f[j-dis[i]]+pow[i]; 78 } 79 } 80 for(i = 0;i <= sum;i++) 81 if(f[i] > spow/2) 82 { 83 printf("%d\n",i); 84 break; 85 } 86 } 87 } 88 return 0; 89 }
floyd
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1 #include <stdio.h> 2 #include <string.h> 3 #define maxn 10000050 4 int map[105][105]; 5 int dis[105]; 6 void inint(int n) 7 { 8 int j,i; 9 for(i = 0;i <= n;i++) 10 { 11 for(j = 0;j <= n;j++) 12 if(i != j)map[i][j] = maxn; 13 else map[i][j] = 0; 14 } 15 } 16 17 int main() 18 { 19 int T,n,m,i,j,k,a,b,c,sum,pow[105],spow,f[100005]; 20 scanf("%d",&T); 21 while(T--) 22 { 23 scanf("%d %d",&n,&m); 24 inint(n); 25 for(i = 0;i < m;i++) 26 { 27 scanf("%d%d%d",&a,&b,&c); 28 if(c < map[a][b]) 29 map[a][b] = map[b][a] = c; 30 } 31 32 spow = sum = 0; 33 for(i = 1;i <= n;i++) 34 scanf("%d",pow+i),spow+=pow[i]; 35 36 for(k = 0;k <= n;k++) 37 { 38 for(i = 0;i <= n;i++) 39 { 40 for(j = 0;j <= n;j++) 41 if(map[i][j] > map[i][k]+map[k][j]) 42 map[i][j] = map[i][k]+map[k][j]; 43 } 44 } 45 46 for(i = 1;i <= n;i++) 47 { 48 dis[i] = map[0][i]; 49 if(dis[i] != maxn) 50 sum += dis[i]; 51 } 52 53 memset(f,0,sizeof(f)); 54 for(i = 1;i <= n;i++) 55 { 56 for(j = sum;j >= dis[i];j--) 57 if(f[j] < f[j-dis[i]] + pow[i]) 58 f[j] = f[j-dis[i]] + pow[i]; 59 } 60 61 for(i = 0;i <= sum;i++) 62 { 63 if(f[i] >= spow/2+1) 64 { 65 printf("%d\n",i); 66 break; 67 } 68 } 69 if(i > sum) 70 puts("impossible"); 71 } 72 return 0; 73 }