一本通 1261：例9.5城市交通路网

Posted 2022-01-01 benjamin-cpp

城市交通路网

最短路 + 路径输出

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Code:

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
//Mystery_Sky
//
#define M 1000100
#define INF 0x3f3f3f3f
struct Edge
    int to, next, w;
edge[M];

int n, m;
int map[5000][5000];
int head[M], cnt, dis[M], vis[M];
inline void add_edge(int u, int v, int w)

    edge[++cnt].to = v;
    edge[cnt].next = head[u];
    edge[cnt].w = w;
    head[u] = cnt;


struct node 
    int dis;
    int pos;
    inline bool operator <(const node &x) const
        return x.dis < dis;
    
;
priority_queue <node> q;
inline void dijkstra()

    memset(dis, INF, sizeof(dis));
    dis[1] = 0;
    q.push((node)0, 1);
    while(!q.empty()) 
        node top = q.top();
        q.pop();
        int x = top.pos;
        if(vis[x]) continue;
        vis[x] = 1;
        for(int i = head[x]; i; i = edge[i].next) 
            int y = edge[i].to;
            if(dis[y] > dis[x] + edge[i].w) 
                dis[y] = dis[x] + edge[i].w;
                if(!vis[y]) q.push((node)dis[y], y); 
            
        
     


void print(int i) 
    if(i == 1) return;
    for(int k = 1; k <= n; k++) 
        if(dis[k] + map[k][i] == dis[i]) 
            print(k);
            printf("%d ", k);
            return;
        
    


int main() 
    scanf("%d", &n);
    int a;
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= n; j++) 
            scanf("%d", &map[i][j]);
            if(map[i][j]) add_edge(i, j, map[i][j]);
        
    dijkstra();
    printf("minlong=%d\n", dis[n]);
    print(n);
    printf("%d\n", n);
    return 0;