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 from left to right.
- The first integer of each row is greater than the last integer of the previous row.
For example,
Consider the following matrix:
[ [1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 50] ]
Given target = 3
, return true
.
参考:http://m.blog.youkuaiyun.com/blog/Jeanphorn/47028041
code:
public class Solution74 {
public boolean searchMatrix(int[][] matrix, int target) {
if(matrix == null || matrix.length==0)
return false;
int i = 0, j = matrix[0].length-1;
while(i<matrix.length && j>=0){
if(target == matrix[i][j]){
return true;
}
else if(target<matrix[i][j])
j--;
else
i++;
}
return false;
}
}