2017冬季24集训模拟-1.寻找幽灵
————————————————————————————————————————————题解
把最短路处理出来然后做背包
没有把head数组和all初始化qwq
1 #include <iostream> 2 #include <queue> 3 #include <set> 4 #include <cstdio> 5 #include <cstring> 6 #include <vector> 7 #include <algorithm> 8 #define siji(i,x,y) for(int i=x;i<=y;++i) 9 #define gongzi(j,x,y) for(int j=x;j>=y;--j) 10 #define xiaosiji(i,x,y) for(int i=x;i<y;++i) 11 #define sigongzi(j,x,y) for(int j=x;j>y;--j) 12 #define ivorysi 13 #define inf 0x5f5f5f5f 14 #define mo 97797977 15 #define ha 974711 16 #define ba 47 17 #define fi first 18 #define se second 19 #define pii pair<int,int> 20 typedef long long ll; 21 using namespace std; 22 struct node { 23 int to,next,val; 24 }edge[20005]; 25 int head[105],sumedge; 26 int n,m,num[105],all,T,ans; 27 int dist[105],f[20005],vis[105]; 28 void add(int u,int v,int c) { 29 edge[++sumedge].to=v; 30 edge[sumedge].next=head[u]; 31 edge[sumedge].val=c; 32 head[u]=sumedge; 33 } 34 void spfa(int u) { 35 vis[u]=1; 36 for(int i=head[u];i;i=edge[i].next) { 37 int v=edge[i].to,w=edge[i].val; 38 if(dist[u]+w < dist[v]) { 39 dist[v]=dist[u]+w; 40 if(!vis[v]) { 41 spfa(v); 42 } 43 } 44 } 45 vis[u]=0; 46 } 47 void init() { 48 scanf("%d%d",&n,&m); 49 int u,v,w; 50 sumedge=0; 51 memset(head,0,sizeof(head)); 52 all=0; 53 siji(i,1,m) { 54 scanf("%d%d%d",&u,&v,&w); 55 ++u,++v; 56 add(u,v,w); 57 add(v,u,w); 58 } 59 siji(i,2,n+1) {scanf("%d",&num[i]);all+=num[i];} 60 dist[1]=0; 61 siji(i,2,n+1) dist[i]=inf; 62 spfa(1); 63 f[0]=0; 64 siji(i,1,all) f[i]=inf; 65 ans=inf; 66 } 67 void solve() { 68 scanf("%d",&T); 69 while(T--) { 70 init(); 71 siji(i,2,n+1) { 72 if(dist[i]>=inf) continue; 73 gongzi(j,all,num[i]) { 74 if(f[j-num[i]] < f[j]-dist[i]) { 75 f[j]=f[j-num[i]]+dist[i]; 76 } 77 } 78 } 79 int half=all/2+1; 80 siji(i,half,all) { 81 if(ans>f[i]) ans=f[i]; 82 } 83 if(ans>=inf) puts("impossible"); 84 else printf("%d\n",ans); 85 } 86 } 87 int main(int argc, char const *argv[]) 88 { 89 #ifdef ivorysi 90 freopen("release.in","r",stdin); 91 freopen("release.out","w",stdout); 92 #else 93 freopen("f1.in","r",stdin); 94 #endif 95 solve(); 96 return 0; 97 }
