ZOJ 1649 Rescue (with enemy maze BFS), zojbfs

ZOJ 1649 Rescue (with enemy maze BFS), zojbfs

The minimum time required to go from the position to the r position in the maze through the '.' square requires 1 s to go through the 'X' square. It takes two second' # 'to represent the wall.

In the case of 1 s and 2 s, you need to make some judgments on the base maze bfs.

The time to arrive at each point is initially infinite. When the time used to arrive at the point from a point is later than the original time hour, the system updates the time at the point and scans the complete graph to obtain the answer.

#include<cstdio>#include<cstring>#include<queue>using namespace std;const int N = 205;char mat[N][N];int time[N][N], sx, sy;int dx[4] = {0, 0, -1, 1};int dy[4] = { -1, 1, 0, 0};struct grid{    int x, y;    grid(int xx = 0, int yy = 0): x(xx), y(yy) {}};void bfs(){    memset(time, 0x3f, sizeof(time));    time[sx][sy] = 0;    queue<grid> g;    g.push(grid(sx, sy));    while(!g.empty())    {        grid cur = g.front();        g.pop();        int cx = cur.x, cy = cur.y, ct = time[cx][cy];        for(int i = 0; i < 4; ++i)        {            int nx = cx + dx[i], ny = cy + dy[i];            if(mat[nx][ny] && mat[nx][ny] != '#')            {                int tt = ct + 1;                if(mat[cx][cy] == 'x') ++tt;                if(tt < time[nx][ny])                {                    time[nx][ny] = tt;                    g.push(grid(nx, ny));                }            }        }    }}int main(){    int n, m, ex, ey;    while (~scanf("%d%d", &n, &m))    {        memset(mat, 0, sizeof(mat));        for(int i = 1; i <= n; ++i)            scanf("%s", mat[i] + 1);        for(int i = 1; i <= n; ++i)            for(int j = 1; j <= m; ++j)                if(mat[i][j] == 'a') sx = i, sy = j;                else if(mat[i][j] == 'r') ex = i, ey = j;        bfs();        if(time[ex][ey] != time[0][0])            printf("%d\n", time[ex][ey]);        else            printf("Poor ANGEL has to stay in the prison all his life.\n");    }    return 0;}