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#include "leetcode.h"
class Solution {
public:
bool exist(vvd(char) & board, string word) {
int dirs[5] = {0, -1, 0, 1, 0};
map<char, int> cnt;
int m = board.size(), n = board[0].size(), l = word.size();
for (char c : word)
cnt[c] += 1;
if (cnt[word[0]] > cnt[word[l - 1]])
reverse(word.begin(), word.end());
function<bool(int, int, int)> dfs;
dfs = [&](int i, int j, int s) -> bool {
if (s == l)
return true;
if (i < 0 or i >= m or j < 0 or j >= n)
return false;
if (board[i][j] != word[s])
return false;
board[i][j] = '#';
for (int d = 0; d < 4; ++d)
if (dfs(i + dirs[d], j + dirs[d + 1], s + 1))
return true;
board[i][j] = word[s];
return false;
};
for (int i = 0; i < m; ++i)
for (int j = 0; j < n; ++j)
if (dfs(i, j, 0))
return true;
return false;
}
};
int main() {
Solution obj;
vvd(char) board = {
{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'}, {'A', 'D', 'E', 'E'}};
string word = "ABCCED";
if (obj.exist(board, word))
cout << "true";
else
cout << "false";
}
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