Search a 2D Matrix--leetcode

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 from the left to the right.
• The first integer of each row was greater than the last integer of the previous row.

For example,

Consider the following matrix:

[  [1,   3,  5,  7],  [Ten, One,],  [23, 30, 34, 50]]

Given target = 3 , return true .

The main topic: to a m*n matrix, each row is ascending and orderly, progressive is also incremental, requires the design of an efficient algorithm to check whether the target element exists in this matrix.

Problem-solving ideas: The entire matrix can be expanded, is a long array, the length of the array is m*n, with two points to find, it is necessary to find the location of the two sub-matrix subscript. Suppose there is a row row, col column, then the element in the matrix corresponding to the key should be matrix[key/col][key%col], and then the binary search.

Talk is cheap>>

  　　  Public BooleanSearchmatrix (int[] Matrix,inttarget) {        if(Matrix = =NULL|| Matrix[0][0] >target)return false; intRowlen =matrix.length; intCollen = matrix[0].length; intLow = 0, high = Rowlen * colLen-1;  while(Low <=High ) {            intMid = (low + high) >>> 1; intx = mid/Collen; inty = mid%Collen; if(Matrix[x][y] >target) { High= Mid-1; } Else if(Matrix[x][y] <target) { Low= Mid + 1; } Else {                return true; }        }        return false; }

Search a 2D matrix--leetcode