sgu 240 Runaway （spfa）

题意：N点M边的无向图，边上有线性不下降的温度，给固定入口S，有E个出口。逃出去，使最大承受温度最小。输出该温度，若该温度超过H，输出-1。

羞涩的题意

显然N*H的复杂度dp[n][h]表示到达n最大温度为h的最小时间（由于温度不下降，这样不会更差，故可以这么搞）

一开始读错题了，以为是温度累加什么鬼...

然后分别写了2种方法，二分和不二分的

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <cmath>
 #include <algorithm>
 #include <vector>
 #include <string>
 #include <set>
 #include <queue>
 using namespace std;

 #define ll long long
 #define MP make_pair

 #define inf 0x3f3f3f3f
 #define eps 1e-8

 #define maxn 110
 struct edge{
     int v,nxt;
     int w,r,p;
 }e[maxn*maxn*];
 int head[maxn], sz;
 void init(){sz=;memset(head,-,sizeof(head));}
 void addedge(int u,int v,int w,int ri,int pi){
     e[sz].v=v,e[sz].nxt=head[u];
     e[sz].w=w,e[sz].r=ri,e[sz].p=pi;
     head[u]=sz++;
 }
 int dp[maxn][];
 bool ed[maxn];
 bool ins[maxn][];
 int pre[maxn][][];
 int getout;
 void dfs(int u,int hp,int S,int cnt){
     if(u==S){printf("%d %d",cnt+,u);return ;}
     dfs(pre[u][hp][],pre[u][hp][],S,cnt+);
     printf(" %d",u);
 }
 bool check(int mahp, int S){
     memset(dp,0x3f,sizeof(dp));
     dp[S][] = ;
     memset(ins,false,sizeof(ins));
     ins[S][] = true;
     queue<pair<int,int> >que;
     que.push(MP(S,));
     if(ed[S]){getout = S;return true;}
     while(!que.empty()){
         int u = que.front().first;
         int hp = que.front().second;
         int t = dp[u][hp];
         que.pop();
         ins[u][hp] = false;
         for(int i=head[u];i!=-;i=e[i].nxt){
             int v = e[i].v;
             int w = e[i].w;
             int r = e[i].r;
             int p = e[i].p;
             ll tmp = r+p*(t+w);
             if(tmp>mahp) continue;
             int hp2 = max(hp,int(tmp));
             if(dp[v][hp2]>dp[u][hp]+w){
                 pre[v][hp2][] = u;
                 pre[v][hp2][] = hp;
                 if(ed[v]){getout = v;return true;}
                 dp[v][hp2] = dp[u][hp]+w;
                 if(ins[v][hp2]==false){
                     ins[v][hp2] = true;
                     que.push(MP(v,hp2));
                 }
             }
         }
     }
     return false;
 }
 int main(){
     int n,m,H,S,E;
     while(~scanf("%d%d%d%d%d",&n,&m,&H,&S,&E)){
         memset(ed,false,sizeof(ed));
         init();
         for(int i=;i<m;++i){
             int u,v,w,r,p;
             scanf("%d%d%d%d%d",&u,&v,&w,&r,&p);
             addedge(u,v,w,r,p);
             addedge(v,u,w,r,p);
         }
         for(int i=;i<E;++i){
             int tmp;
             scanf("%d",&tmp);
             ed[tmp] = true;
         }
         int l=,r=H+;
         while(l<r){
             int mid = (l+r)/;
             if(check(mid,S)) r = mid;
             else l = mid+;
         }
         if(r<=H){
             puts("YES");
             printf("%d\n",r);
             check(r,S);
             dfs(getout,r,S,);
             puts("");
         }else puts("NO");
     }
     return ;
 }

二分代码

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <cmath>
 #include <algorithm>
 #include <vector>
 #include <string>
 #include <set>
 #include <queue>
 using namespace std;

 #define ll long long
 #define MP make_pair

 #define inf 0x3f3f3f3f
 #define eps 1e-8

 #define maxn 110
 struct edge{
     int v,nxt;
     int w,r,p;
 }e[maxn*maxn*];
 int head[maxn], sz;
 void init(){sz=;memset(head,-,sizeof(head));}
 void addedge(int u,int v,int w,int ri,int pi){
     e[sz].v=v,e[sz].nxt=head[u];
     e[sz].w=w,e[sz].r=ri,e[sz].p=pi;
     head[u]=sz++;
 }
 int dp[maxn][];
 bool ed[maxn];
 bool ins[maxn][];
 int pre[maxn][][];
 void dfs(int u,int hp,int S,int cnt){
     if(u==S){printf("%d %d",cnt+,u);return ;}
     dfs(pre[u][hp][],pre[u][hp][],S,cnt+);
     printf(" %d",u);
 }
 pair<int,int> spfa(int mahp, int S){
     int getout=-,ans = mahp+;
     memset(dp,0x3f,sizeof(dp));
     dp[S][] = ;
     memset(ins,false,sizeof(ins));
     ins[S][] = true;
     queue<pair<int,int> >que;
     que.push(MP(S,));
     if(ed[S]) return MP(S,);
     while(!que.empty()){
         int u = que.front().first;
         int hp = que.front().second;
         int t = dp[u][hp];
         que.pop();
         ins[u][hp] = false;
         if(hp>=ans) continue;
         for(int i=head[u];i!=-;i=e[i].nxt){
             int v = e[i].v;
             int w = e[i].w;
             int r = e[i].r;
             int p = e[i].p;
             ll tmp = r+p*(t+w);
             if(tmp>mahp) continue;
             int hp2 = max(hp,int(tmp));
             if(hp2>=ans) continue;
             if(dp[v][hp2]>dp[u][hp]+w){
                 pre[v][hp2][] = u;
                 pre[v][hp2][] = hp;
                 if(ed[v]){
                     getout = v;
                     ans = hp2;
                 }
                 dp[v][hp2] = dp[u][hp]+w;
                 if(ins[v][hp2]==false){
                     ins[v][hp2] = true;
                     que.push(MP(v,hp2));
                 }
             }
         }
     }
     return MP(getout,ans);
 }
 int main(){
     int n,m,H,S,E;
     while(~scanf("%d%d%d%d%d",&n,&m,&H,&S,&E)){
         memset(ed,false,sizeof(ed));
         init();
         for(int i=;i<m;++i){
             int u,v,w,r,p;
             scanf("%d%d%d%d%d",&u,&v,&w,&r,&p);
             addedge(u,v,w,r,p);
             addedge(v,u,w,r,p);
         }
         for(int i=;i<E;++i){
             int tmp;
             scanf("%d",&tmp);
             ed[tmp] = true;
         }
         pair<int,int> cur = spfa(H,S);
         int getout = cur.first;
         int ans = cur.second;
         if(getout!=-){
             puts("YES");
             printf("%d\n",ans);
             dfs(getout,ans,S,);
             puts("");
         }else puts("NO");
     }
     return ;
 }

非二分代码