PAT 1018. Public Bike Management

简单的dfs（写成了最短路），写了一下午，纪念一下。。。

#include<stdio.h>#include<string.h>#include<string>#include<iostream>#include<queue>#include<stack>#include<math.h>#include<string>#include<algorithm>#include<map>using namespace std;int C,N,S,M;int save[510];//每个点的车数 struct node{int x;int l;};vector<node>a[510];struct point{//一个暂时路径 int l;//路径长度 int x;//该路径当前节点 vector<int>r;//路径 int take;//到达该点需从起点携带的自行车 int off;//到达该节点获得的自行车 bool operator < (const point& t)const{return l >= t.l;}};void find(){int path[510];//保存最短路径长 memset(path,0x3f3f3f3f,sizeof(path));bool book[510];//记录已经经过的节点//注意，已经经过了的节点仍有可能重走，因为每次搜是不同的路径 memset(book,false,sizeof(book));point x;x.x = 0;x.l = 0;x.off = x.take = 0;x.r.push_back(0);path[0] = 0;priority_queue<point>q;q.push(x);point r;r.l = 0x3f3f3f3f;while(!q.empty()){x = q.top();q.pop();if(x.l > r.l)break;if(x.x == S && x.l <= r.l){if(x.l < r.l){r = x;}else{if(x.take < r.take){r = x;}else if(x.take == r.take ){if(x.off < r.off){r = x;}}}}if(book[x.x] == false || (x.l == path[x.x])){//该点没走过，或者同样短的路径长，则需要重走 book[x.x] = true;for(int i=0;i<a[x.x].size();i++){if(path[x.x] + a[x.x][i].l <= path[a[x.x][i].x]){path[a[x.x][i].x] = path[x.x] + a[x.x][i].l;point temp = x;temp.l = path[a[x.x][i].x];temp.x = a[x.x][i].x;if(save[a[x.x][i].x] >= C/2){//判断自行车是不足还是剩余 temp.off += save[a[x.x][i].x] - C/2;}else{if(temp.off + save[a[x.x][i].x] >= C/2){temp.off -= C/2 - save[a[x.x][i].x];}else{temp.take += (C/2 - save[a[x.x][i].x] - temp.off);temp.off = 0;}}temp.r.push_back(a[x.x][i].x);q.push(temp);}}}}printf("%d ",r.take);for(int i=0;i<r.r.size();i++){printf("%d",r.r[i]);if(i == r.r.size()-1)printf(" ");else printf("->");}printf("%d\n",r.off);}int main(){scanf("%d%d%d%d",&C,&N,&S,&M);for(int i=1;i<=N;i++){scanf("%d",&save[i]);}for(int i=0;i<M;i++){int x,y,z;scanf("%d%d%d",&x,&y,&z);node t;t.x = x;t.l = z;a[y].push_back(t);t.x = y;a[x].push_back(t);}find();return 0;}