[PAT] A1030 Travel Plan

Posted 2021-02-18 yue36

（经典算法 要熟练运用!）

题目大意

找最短路径，若路径长度相同，找最小花费。

AC代码

邻接矩阵

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<iostream>
#include<string.h>
#include<vector>
#include<algorithm>
#define INF 1000000000
#define MAXV 600
using namespace std;
struct node {
	int v;
	int dis;
	int cost;
};
vector<node>G[MAXV];
int dis[MAXV], c[MAXV];
bool vis[MAXV] = { false };
int pre[MAXV];
int n;
void Dijkstra(int begin) {
	fill(dis, dis + MAXV, INF);
	fill(c, c + MAXV, INF);
	dis[begin] = 0;
	c[begin] = 0;
	int i, j;
	for (i = 0;i < n;i++) {
		pre[i] = i;
	}
	for (i = 0;i < n;i++) {
		int min = INF, u = -1;
		for (j = 0;j < n;j++) {
			if (vis[j] == false && dis[j] < min) {
				min = dis[j];
				u = j;
			}
		}
		if (u == -1)return;
		vis[u] = true;
		for (j = 0;j < G[u].size();j++) {
			int v = G[u][j].v;
			if (vis[v] == false && dis[v] > dis[u] + G[u][j].dis) {
				dis[v] = dis[u] + G[u][j].dis;
				c[v] = c[u] + G[u][j].cost;
				pre[v] = u;
			}
			else if (vis[v] == false && dis[v] == dis[u] + G[u][j].dis) {
				if (c[v] > c[u] + G[u][j].cost) {
					c[v] = c[u] + G[u][j].cost;
					pre[v] = u;
				}
			}
		}
	}
	return;
}
void DFS(int s, int v) {
	if (v == s) {
		printf("%d", s);
		return;
	}
	DFS(s, pre[v]);
	printf(" %d", v);
}
int main() {
	int m, s, d;
	scanf("%d%d%d%d", &n, &m, &s, &d);
	int i, j;
	int u, v;
	for (i = 0;i < m;i++) {
		node tempnode;
		scanf("%d%d%d%d", &u, &v, &tempnode.dis, &tempnode.cost);
		tempnode.v = v;
		G[u].push_back(tempnode);
		tempnode.v = u;
		G[v].push_back(tempnode);
	}
	Dijkstra(s);
	DFS(s, d);
	printf(" %d %d", dis[d], c[d]);
	return 0;
}