ACM-ZOJ 2110 DFS

最新推荐文章于 2018-08-02 21:16:36 发布

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本文介绍了一种基于深度优先搜索的迷宫逃脱算法实现。通过递归方式探索从起点到终点的所有可能路径，并考虑特定步数限制下是否能成功到达目的地。文章详细展示了算法流程、边界条件判断及实现细节。

#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

void DFS(int si, int sj, int count);

int N, M, T;
char map[7][7];
int si(0), sj(0); //S's coordinate
int di(0), dj(0); //D's coordinate
bool survive(false);

int main() {
    while ( scanf("%d%d%d", &N, &M, &T), N&&M&&T ) {
        //getchar();
        survive = false;
        //input
        int wall(0);
        int i, j;
        for ( i = 0; i < N; ++i){
            scanf("%s", map[i]);
            for( j = 0; j < M; ++j ) {
                if ('S' == map[i][j]) { si = i;  sj = j; }
                else if('D' == map[i][j])  { di = i;  dj = j; }
                else if('X' == map[i][j])  ++wall;
            }
        }

        if ( N*M - wall <= T ) {
            printf("NO\n");
            continue;
        }

        map[si][sj] = 'X';
        DFS(si, sj, 0);
        if( survive ) printf("YES\n");
        else printf("NO\n");
    }
}

void DFS(int si, int sj, int count) {
    int move[4][2] = { {0, -1}, {0, 1}, {-1,0}, {1, 0} };
    if (si >= N || sj >= M || si < 0 || sj < 0) return ;
    if (si == di && sj == dj && count == T)  {survive = true;  return ;}

    int temp = (T - count) - abs(si - di) - abs(sj - dj);
    if (temp < 0 || temp%2) return ;

    int i(0);
    for ( i = 0; i < 4; ++i ) {
        int mi = si + move[i][0];
        int mj = sj + move[i][1];
        if (map[mi][mj] != 'X') {
            map[mi][mj] = 'X';
            DFS(mi, mj, count + 1);
            if (survive) return ;
            map[mi][mj] = '.';
        }
    }
    return ; //all is wall
}