Search a 2D Matrix II

最新推荐文章于 2021-03-02 01:17:16 发布

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本文介绍了一种在具有特定排序属性的二维矩阵中查找目标值的高效算法。矩阵中的每行从左到右递增排序，每列从上到下递增排序。通过算法实例演示了如何快速定位目标值。

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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.

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