*LeetCode 79. Word Search DFS

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https://leetcode.com/problems/word-search/
#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <stack>#include <vector>using namespace std;const int SIZE = 129;class Solution {public:    bool exist(vector<vector<char> >& board, string word) {        int bhash[SIZE] = {0};        int whash[SIZE] = {0};        for(int i=0;i<board.size();i++) {            for( int j=0; j<board[i].size(); j++ ) {                bhash[ board[i][j] ] ++;            }        }        for( int i=0; i<word.size(); i++ ) {            whash[ word[i] ] ++;        }        for(int i=0;i<SIZE;i++) {            if(whash[i] > bhash[i])return false;        }        int flag = 0;        if(board.size() == 0) return false;        int mat[SIZE][SIZE];        for(int i=0; i<board.size(); i++) {            for(int j=0; j<board[i].size(); j++) {                memset(mat, 0, sizeof(mat));                flag = dfs(i, j, board, word, mat);                if( flag ) return true;            }        }        return false;    }    bool dfs(int h, int lie, vector< vector<char> > &board, string wd, int mat[SIZE][SIZE]) {        bool ret = false;        if(wd[0] != board[h][lie] || mat[h][lie] )return false;        mat[h][lie] = 1;        if(wd.size() == 1 ) return true;        ret= ( h-1>=0 && dfs(h-1, lie, board, wd.substr(1), mat) ) ||                ( h+1 < board.size() && dfs(h+1, lie, board, wd.substr(1), mat) ) ||                ( lie-1>=0 && dfs(h, lie-1, board, wd.substr(1), mat) ) ||                ( lie+1<board[0].size() && dfs(h, lie+1, board, wd.substr(1), mat) );        mat[h][lie] = 0; //忘记写了  WA了，，        return ret;        //up down left right    }};int main() {    freopen( "79.txt", "r", stdin );    string word;    int n;    while( cin >> n ) {        vector < vector<char> > board;        for(int i=0;i<n;i++) {            cin >> word;            vector <char> tmp;            for( int j=0;j<word.size(); j++ ) {                tmp.push_back(word[j]);            }            board.push_back(tmp);        }        cin >> word;        Solution s;        cout << s.exist(board, word);    }    return 0;}
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