58 单词搜索

1.题目描述

2.代码及注释

 bool backtracking(vector<vector<char>>& board, string word, int i, int j, int index,
    vector<vector<int>>& visited){
         int row = board.size();//行
        int col = board[0].size();//列
        if(i<0 || j<0 || i>row-1 || j>col-1 || word[index]!=board[i][j]|| visited[i][j] == 1){
            return false;//当前坐标越界直接返回false
        }
        if(index == word.length()-1){
            return true;
        }
        visited[i][j] = 1;//标记一访问当前坐标(i,j);
        bool top = backtracking(board,word,i-1,j,index+1,visited);
        bool left = backtracking(board,word,i,j-1,index+1,visited);
        bool down = backtracking(board,word,i+1,j,index+1,visited);
        bool right = backtracking(board,word,i,j+1,index+1,visited);
        bool res = (top||left||down||right);
        visited[i][j] = 0;
        return res;    
    }
    bool exist(vector<vector<char>>& board, string word) {
        int row = board.size();//行
        int col = board[0].size();//列
        vector<vector<int>> visited(row,vector<int>(col,0));//初始化row*col二维矩阵初始化0
        for(int i = 0; i <= row-1; i++){//每个位置都遍历
            for(int j = 0; j <= col-1; j++){
                if(backtracking(board,word,i,j,0,visited)){
                    return true;
                }
            }
        }
        return false;
        
    }

bool backtracking(char** board,int i, int j, int** visited,char* word,
int index,int rowSize,int colSize ){
    
    if(i<0 || j<0||i>rowSize-1||j>colSize-1||visited[i][j]==1||board[i][j]!=word[index]){
        return false;
    }
    if(index == strlen(word) - 1){
        return true;
    }
    visited[i][j] = 1;//标记已访问，防止（比如）右边的元素向左回头访问当前元素
    bool top = backtracking(board,i-1,j,visited,word,index+1,rowSize,colSize);
    bool left = backtracking(board,i,j-1,visited,word,index+1,rowSize,colSize);
    bool down = backtracking(board,i+1,j,visited,word,index+1,rowSize,colSize);
    bool right = backtracking(board,i,j+1,visited,word,index+1,rowSize,colSize);
    bool res = (top||left||down||right);
    visited[i][j] = 0;
    return res;

}




bool exist(char** board, int boardSize, int* boardColSize, char* word) {
    int row = boardSize;
    int col = boardColSize[0];
    //分配visited的内存
    int** visited = (int**)malloc(sizeof(int*)*row);
    //为每行分配内存
    for(int i=0;i<=row-1;i++){
        visited[i] = (int*)malloc(sizeof(int)*col);
        for(int j = 0;j<=col-1;j++){
            visited[i][j]=0;
        }
    }
    for(int i = 0;i<=row-1;i++){
        for(int j = 0;j<=col-1;j++){
            if(backtracking(board,i,j,visited,word,0,row,col)){
                return true;
            }
        }
    }
    return false;
    
}