Leetcode 240. Search a 2D Matrix II

Write an efficient algorithm, searches for a value in a m x n Matrix. This matrix has the following properties:

• Integers in each row is sorted in ascending from left to right.
• Integers in each column is sorted in ascending from top to bottom.

For example,

Consider the following matrix:

[  [1,   4,  7, one, a],  [2,   5, 8,, +  ],  [3,   6,  9, +, +],  [10, 13, 14, 17,  [18, 21, 23, 26, 30]

Given target = 5 , return true .

Given target = 20 , return false .

Problem Solving Ideas:

From the lower left corner to the upper right corner of the search, if the target is less than the right to find, if greater than target to look up. Time complexity O (m+n) n is the number of rows and M is the number of columns.

For example, looking for 136

But lintcode on a similar topic to find out how many target, loop slightly change under, set a count, on it.

Java Code:

 Public classSolution { Public BooleanSearchmatrix (int[] Matrix,inttarget) {        //Check Corner case        if(Matrix = =NULL|| Matrix.length = = 0) {            return false; }        if(Matrix[0] = =NULL|| Matrix[0].length = = 0) {            return false; }        //find from bottom left to top right        intn = matrix.length;//Row        intm = matrix[0].length;//column        intx = n-1; inty = 0; while(x >= 0 && y <m) {if(Matrix[x][y] <target) {y++; } Else if(Matrix[x][y] >target) {x--; } Else {                return true; }        }         return false; }}

Reference:

1. http://www.jiuzhang.com/solutions/search-a-2d-matrix-ii/

Leetcode 240. Search a 2D Matrix II