[LeetCode][JavaScript]Search a 2D Matrix II

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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.

https://leetcode.com/problems/search-a-2d-matrix-ii/      從右上方開始，如果當前的數大於target，列號減一(左移一列)，如果當前的數小於target，行號加一(下移一行)。從左下角開始找也是一樣的。

 1 /** 2  * @param {number[][]} matrix 3  * @param {number} target 4  * @return {boolean} 5  */ 6 var searchMatrix = function(matrix, target) { 7     return findTarget(0, matrix[0].length - 1); 8  9     function findTarget(i, j){10         if(matrix[i][j] === target){11             return true;12         }13         if(matrix[i][j] > target){14             if(!matrix[i][j - 1]){15                 return false;16             }else{17                 return findTarget(i, j - 1);18             }19         }20         if(matrix[i][j] < target){21             if(!matrix[i + 1]){22                 return false;23             }else{24                 return findTarget(i + 1, j);25             }26         }27     }28 };

 

 

[LeetCode][JavaScript]Search a 2D Matrix II