1018. Public Bike Management (30) PAT 甲级

#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<vector>
#include<math.h>
using namespace std;

#define MAX_V 510
#define INF 1000000000

int G[MAX_V][MAX_V];
int n,m,Cmax,Sp;
bool visited[MAX_V];
int weight[MAX_V];
int w[MAX_V];
int MinNeed=INF;
int MinRemain=INF;
int d[MAX_V];
vector<int> pre[MAX_V];
vector<int> temp,path;

void Dijkstra(int s){
fill(d,d+MAX_V,INF);
d[s]=0;
for(int i=0;i<=n;i++){
int u=-1,Min=INF;
for(int j=0;j<=n;j++){
if(!visited[j]&&d[j]<Min){
u=j;
Min=d[j];
}
}
if(u==-1)   return ;
visited[u]=true;
for(int v=0;v<=n;v++){
if(!visited[v]&&G[u][v]!=INF){
if(d[u]+G[u][v]<d[v]){
d[v]=d[u]+G[u][v];
pre[v].clear();
pre[v].push_back(u);
}
else if(d[u]+G[u][v]==d[v]){
pre[v].push_back(u);
}
}
}
}
}

void DFS(int v){
if(v==0){
temp.push_back(v);
int need=0,remain=0;
for(int i=temp.size()-1;i>=0;i--){
int vertex=temp[i];
if(weight[vertex]>0){
remain+=weight[vertex];
}
else{
if(remain>abs(weight[vertex])){
remain-=abs(weight[vertex]);
}
else{
need+=abs(weight[vertex])-remain;
remain=0;
}
}
}
if(need<MinNeed){
MinNeed=need;
MinRemain=remain;
path=temp;
}else if(need==MinNeed&&remain<MinRemain){
MinRemain=remain;
path=temp;
}
temp.pop_back();
return;
}
temp.push_back(v);
for(int i=0;i<pre[v].size();i++){
DFS(pre[v][i]);
}
temp.pop_back();
}

int main(){
scanf("%d%d%d%d",&Cmax,&n,&Sp,&m);
fill(G[0],G[0]+MAX_V*MAX_V,INF);
for(int i=1;i<=n;i++){
scanf("%d",&weight[i]);
weight[i]-=Cmax/2;
}
int u,v;
for(int i=0;i<m;i++){
scanf("%d%d",&u,&v);
scanf("%d",&G[u][v]);
G[v][u]=G[u][v];
}
Dijkstra(0);
DFS(Sp);
printf("%d ",MinNeed);
for(int i=path.size()-1;i>=0;i--){
printf("%d",path[i]);
if(i>0) printf("->");
}
printf(" %d",MinRemain);
}