2018年东北农业大学春季校赛 D wyh的迷宫 【BFS】

题目链接

https://www.nowcoder.com/acm/contest/93/D

思路

BFS模板题

AC代码

#include <cstdio>
#include <cstring>
#include <ctype.h>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <map>
#include <stack>
#include <set>
#include <numeric>
#include <sstream>
#include <iomanip>
#include <limits>

#define CLR(a) memset(a, 0, sizeof(a))
#define pb push_back

using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef pair<string, int> psi;
typedef pair<string, string> pss;

const double PI = 3.14159265358979323846264338327;
const double E = exp(1);
const double eps = 1e-30;

const int INF = 0x3f3f3f3f;
const int maxn = 5e2 + 5;
const int MOD = 1e9 + 7;

char Map[maxn][maxn];

int flag;
int n, m;

int Move[][2] =
{
    -1, 0, // up
     1, 0, // down
     0,-1, // left
     0, 1, // right
};

bool in_range(int x, int y)
{
    return (x >= 0 && x < n && y >= 0 && y < m);
}

queue <pii> q;

void bfs()
{
    int len = q.size();
    for (int i = 0; i < len; i++)
    {
        int x = q.front().first, y = q.front().second;
        q.pop();
        Map[x][y] = 'x';
        for (int j = 0; j < 4; j++)
        {
            int next_x = x + Move[j][0];
            int next_y = y + Move[j][1];
            if (in_range(next_x, next_y) && Map[next_x][next_y] != 'x')
            {
                if (Map[next_x][next_y] == 't')
                {
                    flag = 1;
                    return;
                }
                else
                {
                    Map[next_x][next_y] = 'x';
                    q.push(pii(next_x, next_y));
                }
            }
        }
    }
    if (q.size())
        bfs();
}

int main()
{
    int T;
    scanf("%d", &T);
    while (T--)
    {
        scanf("%d%d ", &n, &m);
        int x = -1, y = -1;
        for (int i = 0; i < n; i++)
        {
            scanf("%s", Map[i]);
            if (x == -1)
                for (int j = 0; j < m; j++)
                {
                    if (Map[i][j] == 's')
                        x = i, y = j;
                }
        }
        while (!q.empty())
            q. pop();
        q.push(pii(x, y));
        //cout << q.size() << endl;
        flag = 0;
        bfs();
        //for (int i = 0; i < n; i++)
        //  printf("%s\n", Map[i]);
        if (flag)
            printf("YES\n");
        else
            printf("NO\n");
    }
}