一本通 1261：【例9.5】城市交通路网

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;
}