Search a 2D Matrix II

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最新推荐文章于 2025-01-17 23:23:30 发布

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本文介绍了一种高效的矩阵搜索算法，该算法能在排序矩阵中查找特定值。矩阵特点为每行每列均按升序排列，算法从左上角开始，根据目标值调整搜索方向。

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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.

从左上角开始，大于target向前，小于向下。

public class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        if(matrix==null||matrix.length<=0)
			return false;
		int m=matrix.length;
		int n=matrix[0].length;
		int i=0,j=n-1;
		while(i<m&&j>=0){
			int tmp=matrix[i][j];
			if(tmp>target)
				j--;
			else if(tmp<target)
				i++;
			else
				return true;
		}
		return false;
    }
}