[LeetCode 240] 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.

solution:

search from matrix right top element, if smaller than target go left, if larger than target, go down.

met this in Microsoft interview last year.

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

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想象困难做出的反应，不是逃避或绕开它们，