LeetCode 之 Search a 2D Matrix II

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

• Integers in each row are sorted in ascending from left to right.
• Integers in each column are sorted in ascending from top to bottom.

For example,

Consider the following matrix:

[  [1,   4,  7, 11, 15],  [2,   5,  8, 12, 19],  [3,   6,  9, 16, 22],  [10, 13, 14, 17, 24],  [18, 21, 23, 26, 30]]

Given target = 5, return true.

Given target = 20, return false.

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代码如下：

class Solution {public:    bool searchMatrix(vector<vector<int>>& matrix, int target) {        int row=matrix.size();        int col=matrix[0].size();        int _row=0,_col=col-1;        while(_row<row&&_col>=0){            if(matrix[_row][_col]==target)                return true;            else if(matrix[_row][_col]>target)                _col--;            else                _row++;                        }        return false;    }};