74. 搜索二维矩阵

目录

• 题目描述
• 代码

题目描述

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.

代码

class Solution {
public:
    bool searchMatrix(vector<vector<int> > &matrix, int target) {

    	int rows = matrix.size();
    	if(rows == 0)
    		return false;
    	int columns = matrix[0].size();
    	if(columns == 0)
    		return false;

    	int i = 0;
    	int j = columns-1;

    	while(i < rows && j >=0){
    		
    		if(matrix[i][j] == target)
    			return true;
    		else if(matrix[i][j] > target)
    			j--;
    		else
    			i++;
    	}

    	return false;      
    }
};