PAT(A) - 1030. Travel Plan (30)

A traveler's map gives the distances between cities along the highways, together with the cost of each highway. Now you are supposed to write a program to help a traveler to decide the shortest path between his/her starting city and the destination. If such
a shortest path is not unique, you are supposed to output the one with the minimum cost, which is guaranteed to be unique.

Input Specification:

Each input file contains one test case. Each case starts with a line containing 4 positive integers N, M, S, and D, where N (<=500) is the number of cities (and hence the cities are numbered from 0 to N-1); M is the number of highways; S and D are the starting
and the destination cities, respectively. Then M lines follow, each provides the information of a highway, in the format:

City1 City2 Distance Cost

where the numbers are all integers no more than 500, and are separated by a space.

Output Specification:

For each test case, print in one line the cities along the shortest path from the starting point to the destination, followed by the total distance and the total cost of the path. The numbers must be separated by a space and there must be no extra space at
the end of output.
Sample Input

4 5 0 3
0 1 1 20
1 3 2 30
0 3 4 10
0 2 2 20
2 3 1 20

Sample Output

0 2 3 3 40

思路分析：我用的DFS，网上大家用的都是Dijkstra，加栈记录路径。（主要是我Dijkstra写的还不是很熟练......）这道题测试数据很弱，相当弱。另外我发现PAT能过，牛客上的不能过，最小值是正确的，但是路径不对。我写的还是有问题吧，，先贴上来再说。。

#include <cstdio>
#include <vector>
#include <cstring>

#define MAX 500

using namespace std;

int MGraph[MAX][MAX]; // 图
int dist[MAX][MAX]; // 边的路长
int cost[MAX][MAX]; // 花费
int visit[MAX];

int minDist; // 最短路径
int minCost; // 最小花费

vector<int> path; // 最后要输出的路径的数组
vector<int> temp; // 中间记录路径的临时数组

void InsertEdge( int a, int b ) { // 插入边
MGraph[a][b] = 1;
MGraph[b][a] = 1;
}

// DFS搜索
void DFS( int curNode, int end, int n, int d, int c ) {
if( curNode == end ) { // 找到路径
if( d < minDist ) { // 更新结果
minDist = d;
minCost = c;
path = temp;
}
else if( d == minDist ) {
if( c < minCost ) {
minCost = c;
path = temp;
}
}
temp.clear(); // 临时数组清空
//printf( "\n" );
return;
}

if( d > minDist ) { // 剪枝
temp.clear();
//printf( "\n" );
return;
}

for( int i = 0; i < n; i++ ) {
if( !visit[i] && MGraph[curNode][i] == 1 ) {
visit[i] = 1;
//printf( "%d ", i );
temp.push_back( i );
DFS( i, end, n, d + dist[curNode][i], c + cost[curNode][i] );
visit[i] = 0;
}
}
}

int main() {
//freopen( "123.txt", "r", stdin );
int N, M, S, D;
scanf( "%d%d%d%d", &N, &M, &S, &D );

int a, b, d, w;
for( int i = 0; i < M; i++ ) {
scanf( "%d%d%d%d", &a, &b, &d, &w );
InsertEdge( a, b );
dist[a][b] = d;
dist[b][a] = d;
cost[a][b] = w;
cost[b][a] = w;
}

minDist = minCost = 0x3ffffff; // 更开始赋值一个很大的数
visit[S] = 1;
DFS( S, D, N, 0, 0 );
printf( "%d", S );
for( int i = 0; i < path.size(); i++ ) {
printf( " %d", path[i] );
}
printf( " %d %d", minDist, minCost );

return 0;
}