Search a 2D Matrix II

Topic:

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 .

Links: http://leetcode.com/problems/search-a-2d-matrix-ii/

Exercises

Finds the target number in a two-dimensional array sorted in rows and columns. Here we use a very ingenious method, from the top right corner of the matrix to find, equivalent to this element as mid, the target is larger than mid, then row + 1, small col + 1, equal to return to mid. is also similar to the idea of two-point search.

Time Complexity-o (M + N), Space complexity-o (1)

 Public classSolution { Public BooleanSearchmatrix (int[] Matrix,inttarget) {        if(Matrix = =NULL|| Matrix.length = = 0)            return false; introw = 0, col = matrix[0].length-1;  while(Row < matrix.length && Col >= 0) {            intCurelem =Matrix[row][col]; if(Curelem = =target)return true; Else if(Curelem <target) Row++; ElseCol--; }                return false; }}

Test:

Https://leetcode.com/discuss/47506/ac-clean-java-solution

Https://leetcode.com/discuss/48852/my-concise-o-m-n-java-solution

Https://leetcode.com/discuss/66657/java-short-code-o-m-n

Search a 2D Matrix II