[LeetCode 题解]: Search a 2D Matrix

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 from left to right.
• The first integer of each row is greater than the last integer of the previous row.

For example,

Consider the following matrix:

[
  [1,   3,  5,  7],
  [10, 11, 16, 20],
  [23, 30, 34, 50]
]

Given target = 3, return true.

面试宝典上的经典题目，在此不赘述了，按照题目描述，找规律即可。

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

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