PAT 1003. Emergency (25)

1003. Emergency (25)

时间限制

400 ms

内存限制

32000 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

As an emergency rescue team leader of a city, you are given a special map of your country. The map shows several scattered cities connected by some roads. Amount of rescue teams in each city and the length of each road between any pair of cities are marked on the map. When there is an emergency call to you from some other city, your job is to lead your men to the place as quickly as possible, and at the mean time, call up as many hands on the way as possible.

Input

Each input file contains one test case. For each test case, the first line contains 4 positive integers: N (<= 500) - the number of cities (and the cities are numbered from 0 to N-1), M - the number of roads, C1 and C2 - the cities that you are currently in and that you must save, respectively. The next line contains N integers, where the i-th integer is the number of rescue teams in the i-th city. Then M lines follow, each describes a road with three integers c1, c2 and L, which are the pair of cities connected by a road and the length of that road, respectively. It is guaranteed that there exists at least one path from C1 to C2.

Output

For each test case, print in one line two numbers: the number of different shortest paths between C1 and C2, and the maximum amount of rescue teams you can possibly gather.
All the numbers in a line must be separated by exactly one space, and there is no extra space allowed at the end of a line.

Sample Input

5 6 0 21 2 1 5 30 1 10 2 20 3 11 2 12 4 13 4 1

Sample Output

2 4

题目的大意就是求从C1到C2的最短路的条数，和最短路中rescue的最大值，
思路：直接暴力DFS，但是最后一个数据过不了，百度学了枝剪才完全过的

#include <stdio.h>#include <string.h>const int INF = 999999;const int MAXN = 550;int N, M, C1, C2;int map[MAXN][MAXN];bool visit[MAXN];int rescue[MAXN];int count = 0;int maxscue = 0;int minlen = INF;int minlne_scue;void init(){for (int i = 0; i < N; i++){rescue[i] = 0;visit[i] = false;for (int j = 0; j < N; j++){map[i][j] = INF;}}}void dfs(int current, int goal, int len, int num)//当前位置，目标位置，长度和救援队数量{if (current == goal){if (len < minlen)//寻找最小值 {minlen = len;count = 1;//每次找到最小值重新计数 maxscue = num;}else if (len == minlen)//相同的最小值 {count++;maxscue = maxscue>num ? maxscue : num;//跟新最大值 }return ;}if(len > minlen) return;//优化 for (int i = 0; i < N; i++){if (map[current][i] != INF&&visit[i] == false){visit[i] = true;dfs(i, goal, len + map[current][i], num + rescue[i]);visit[i] = false;}}}int main(){//输入 scanf("%d %d %d %d", &N, &M, &C1, &C2);init();for (int i = 0; i < N; i++)scanf("%d", &rescue[i]);for (int i = 0; i < M; i++){int a, b, c;scanf("%d %d %d", &a, &b, &c);if(map[a][b]>c)map[a][b] = map[b][a] = c;}if(C1==C2){printf("1 %d",rescue[C1]); return 0;}visit[C1] = true;//DFS dfs(C1, C2, 0, rescue[C1]);//输出 printf("%d %d", count, maxscue);return 0;}