class Solution {
    
    
public:
    bool findNumberIn2DArray(vector<vector<int>>& matrix, int target) {
    
    
        //记住要判断输入的合法性
        if(matrix.size() == 0 || matrix[0].size() == 0)
            return false;
        int n = matrix.size(), m = matrix[0].size();
        int row = 0, column = m - 1;
        //出范围则说明未查找到
        while(row < n && column >= 0){
    
    
            if(matrix[row][column] == target)
                return true;
            //大于则缩小一列
            else if(matrix[row][column] > target)
                column--;
            //小于则缩小一行
            else    
                row++;
        }
        return false;
    }
};