zoj1649 营救(Rescue) BFS

BFS 搜索另开一个二维数组记录能达到该点的最小步数

代码

  1 // 111111.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
  2 //
  3 
  4 #include <iostream>
  5 #include <vector>
  6 #include <string>
  7 #include <memory.h>
  8 #include <queue>
  9 #include <algorithm>
 10 
 11 using namespace std;
 12 
 13 const int MAXN = 200;
 14 
 15 char g[MAXN][MAXN];
 16 int vis[MAXN][MAXN];
 17 queue<vector<int>> q;
 18 
 19 int n, m;
 20 
 21 int startx = -1;
 22 int starty = -1;
 23 
 24 int endx = -1;
 25 int endy = -1;
 26 
 27 int minWalk = 999999;
 28 
 29 int addx[] = { 1,-1,0,0 };
 30 int addy[] = { 0,0,1,-1 };
 31 
 32 
 33 void bfs()
 34 {
 35     vector<int> start{ startx, starty ,0 };
 36     vis[startx][starty] = 0;
 37     q.push(start);
 38 
 39     while (!q.empty()) {
 40         vector<int> ele = q.front();
 41         q.pop();
 42 
 43         for (int i = 0; i < 4; i++) {
 44             int newx = ele[0] + addx[i];
 45             int newy = ele[1] + addy[i];
 46             int walk = ele[2]+1;
 47 
 48             if (newx >= 0 && newx < n && newy >= 0 && newy < m &&
 49                 (g[newx][newy] != '#')) {
 50                 if (g[newx][newy] == 'x') walk++;
 51                 if (walk < vis[newx][newy]) {
 52                     vis[newx][newy] = walk;
 53                     vector<int> input{newx,newy,walk};
 54                     q.push(input);
 55                 }
 56                 if (g[newx][newy] == 'r') {
 57                     minWalk = min(minWalk, walk);
 58                 }
 59             }//if (newx >= 0 && newx < n && newy >= 0 && newy < m)
 60         }
 61     }
 62 
 63 }
 64 
 65 
 66 
 67 
 68 
 69 int main()
 70 {
 71     while (~scanf("%d%d", &n, &m)) {
 72         minWalk = 999999;
 73 
 74         memset(g, 0, sizeof g);
 75         memset(vis, 0x3f3f3f3f,sizeof vis);
 76         startx = -1; endx = -1;
 77         for (int i = 0; i < n; i++) {
 78             scanf("%s", g[i]);
 79             if (startx == -1) {
 80                 //寻找 起点
 81                 for (int j = 0; j < m; j++) {
 82                     if (g[i][j] == 'a') {
 83                         startx = i; starty = j;
 84                     }
 85                 }
 86             }
 87 
 88             if (endx == -1) {
 89                 //寻找 终点
 90                 for (int j = 0; j < m; j++) {
 91                     if (g[i][j] == 'r') {
 92                         endx = i; endy = j;
 93                     }
 94                 }
 95             }
 96         }
 97 
 98         bfs();
 99         if (minWalk != 999999)
100             printf("%d\n", minWalk);
101         else
102             printf("Poor ANGEL has to stay in the prison all his life.\n");
103     }
104     return 0;
105 }