백준 2589번 C++

#include <iostream>

#include <cstring>

#include <queue>

using namespace std;

const int MAX = 51;

int n,m;

char way[MAX][MAX];

char shortestway[MAX][MAX];

typedef struct {

int x, y;

}Move;

Move moves[4] = { {1,0},{-1,0},{0,1},{0,-1} };

int bfs(int i,int j) {

int longestway=0;

memset(shortestway, 0, sizeof(shortestway));

queue<pair<int,int>> q;

q.push(make_pair(i, j));

while (!q.empty()) {

int x = q.front().first;

int y = q.front().second;

q.pop();

for (int k = 0; k < 4; k++) {

int ma = x + moves[k].x;

int mb = y + moves[k].y;

if (ma >= 0 && ma < n && mb >= 0 && mb < m) {

if (way[ma][mb] == 'L' && shortestway[ma][mb] == 0) {

q.push(make_pair(ma, mb));

shortestway[ma][mb] = shortestway[x][y] + 1;

longestway = shortestway[ma][mb];

}

}

}

}

return longestway;

}

int main(void) {

cin >> n >> m;

for (int i = 0; i < n; i++) {

cin >> way[i];

}

int ans = 0,waycount;

for (int i = 0; i < n; i++) {

for (int j = 0; j < m; j++) {

if (way[i][j] == 'L') {

waycount = bfs(i, j);

if (ans < waycount)

ans = waycount;

}

}

}

cout << ans;

}