zoj1649 营救(Rescue) BFS

地址  https://vjudge.net/problem/ZOJ-1649

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

// 111111.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include <iostream>
#include <vector>
#include <string>
#include <memory.h>
#include <queue>
#include <algorithm>

using namespace std;

const int MAXN = 200;

char g[MAXN][MAXN];
int vis[MAXN][MAXN];
queue<vector<int>> q;

int n, m;

int startx = -1;
int starty = -1;

int endx = -1;
int endy = -1;

int minWalk = 999999;

int addx[] = { 1,-1,0,0 };
int addy[] = { 0,0,1,-1 };


void bfs()
{
    vector<int> start{ startx, starty ,0 };
    vis[startx][starty] = 0;
    q.push(start);

    while (!q.empty()) {
        vector<int> ele = q.front();
        q.pop();

        for (int i = 0; i < 4; i++) {
            int newx = ele[0] + addx[i];
            int newy = ele[1] + addy[i];
            int walk = ele[2]+1;

            if (newx >= 0 && newx < n && newy >= 0 && newy < m &&
                (g[newx][newy] != '#')) {
                if (g[newx][newy] == 'x') walk++;
                if (walk < vis[newx][newy]) {
                    vis[newx][newy] = walk;
                    vector<int> input{newx,newy,walk};
                    q.push(input);
                }
                if (g[newx][newy] == 'r') {
                    minWalk = min(minWalk, walk);
                }
            }//if (newx >= 0 && newx < n && newy >= 0 && newy < m)
        }
    }

}





int main()
{
    while (~scanf("%d%d", &n, &m)) {
        minWalk = 999999;

        memset(g, 0, sizeof g);
        memset(vis, 0x3f3f3f3f,sizeof vis);
        startx = -1; endx = -1;
        for (int i = 0; i < n; i++) {
            scanf("%s", g[i]);
            if (startx == -1) {
                //寻找 起点
                for (int j = 0; j < m; j++) {
                    if (g[i][j] == 'a') {
                        startx = i; starty = j;
                    }
                }
            }

            if (endx == -1) {
                //寻找 终点
                for (int j = 0; j < m; j++) {
                    if (g[i][j] == 'r') {
                        endx = i; endy = j;
                    }
                }
            }
        }

        bfs();
        if (minWalk != 999999)
            printf("%d
", minWalk);
        else
            printf("Poor ANGEL has to stay in the prison all his life.
");
    }
    return 0;
}