L3-007. 天梯地图

L3-007. 天梯地图

题目链接：https://www.patest.cn/contests/gplt/L3-007

Dijstra

这题是Dijstra的变形，麻烦的是两种最短路的相同距离时的选择条件不同，也就是说要写两个Dijstra函数。很早就写完了代码，不过debug了一星期，最后还是参考他人博客才知道自己错哪了= =(易错点已注释)

代码如下：

#include<cstdio>
#include<cstring>
#include<stack>
#define N 505
using namespace std;
const int INF=0x3f3f3f3f;
bool mark[N];
int n,Start,End;
int lenmp[N][N];
int timemp[N][N];
int lendis[N];
int timedis[N];
int lenpre[N];
int timepre[N];
void lenDijstra();
void timeDijstra();
int main(void){
    /**输入**/
    memset(lenpre,-1,sizeof(lenpre));
    memset(timepre,-1,sizeof(timepre));
    int m;
    scanf("%d%d",&n,&m);
    for(int i=0;i<n;++i){
        lendis[i]=INF;
        timedis[i]=INF;
        for(int j=0;j<n;++j){
            lenmp[i][j]=INF;
            timemp[i][j]=INF;
        }
    }
    while(m--){
        int a,b,one,length,time;
        scanf("%d%d%d%d%d",&a,&b,&one,&length,&time);
        if(one){
            lenmp[a][b]=length;
            timemp[a][b]=time;
        }else{
            lenmp[a][b]=lenmp[b][a]=length;
            timemp[a][b]=timemp[b][a]=time;
        }
    }
    scanf("%d%d",&Start,&End);
    /**数据处理**/
    lenDijstra();
    timeDijstra();
    /**输出**/
    int k=End;
    bool flag=1;
    stack<int>times;
    while(k!=Start){
        times.push(k);
        if(timepre[k]!=lenpre[k])flag=0;
        k=timepre[k];
    }
    if(flag){
        printf("Time = %d;",timedis[End]);
        printf(" Distance = %d:",lendis[End]);
        printf("% d",Start);
        while(!times.empty()){
            printf(" => %d",times.top());
            times.pop();
        }
        printf("
");
    }else{
        printf("Time = %d:",timedis[End]);
        printf("% d",Start);
        while(!times.empty()){
            printf(" => %d",times.top());
            times.pop();
        }
        printf("
");
        printf("Distance = %d:",lendis[End]);
        printf("% d",Start);
        stack<int>diss;
        k=End;
        while(k!=Start){
            diss.push(k);
            k=lenpre[k];
        }
        while(!diss.empty()){
            printf(" => %d",diss.top());
            diss.pop();
        }
        printf("
");
    }
    return 0;
}
void lenDijstra(){
    int node[N];
    memset(node,0,sizeof(node));
    node[Start]=1;

    memset(mark,1,sizeof(mark));
    lendis[Start]=0;
    while(1){
        int Min=INF,index;
        for(int i=0;i<n;++i){
            if(mark[i]&&Min>lendis[i]){
                Min=lendis[i];
                index=i;
            }
        }
        if(Min==INF)break;
        mark[index]=0;
        for(int i=0;i<n;++i){
            int d=lendis[index]+lenmp[index][i];
            if(mark[i]&&lendis[i]>d){
                lendis[i]=d;
                lenpre[i]=index;
                node[i]=node[index]+1;                /*非node[i]++*/
            }else if(mark[i]&&lendis[i]==d&&node[index]+1<node[i]){
                lenpre[i]=index;
                node[i]=node[index]+1;
            }
        }
    }
}
void timeDijstra(){
    memset(mark,1,sizeof(mark));
    int dis[N];
    for(int i=0;i<n;++i)
        dis[i]=lenmp[Start][i];
    timedis[Start]=0;
    dis[Start]=0;
    while(1){
        int Min=INF,index;
        for(int i=0;i<n;++i){
            if(mark[i]&&Min>timedis[i]){
                Min=timedis[i];
                index=i;
            }
        }
        if(Min==INF)break;
        mark[index]=0;
        for(int i=0;i<n;++i){
            int t=timedis[index]+timemp[index][i];
            int d=dis[index]+lenmp[index][i];
            if(mark[i]&&timedis[i]>t){
                dis[i]=d;
                timedis[i]=t;
                timepre[i]=index;
            }else if(mark[i]&&timedis[i]==t&&dis[i]>d){
                dis[i]=d;
                timepre[i]=index;
            }
        }
    }
}