leetcode--Search a 2D Matrix
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
.
public class Solution { public boolean searchMatrix(int[][] matrix, int target) { boolean exists = false; if(matrix.length > 0){ int top = 0, bottom = matrix.length - 1; while(top < bottom){ if(matrix[top + (bottom - top) / 2][0] > target) bottom = top + (bottom - top) / 2 - 1; else if(matrix[top + (bottom - top) / 2][0] == target){ exists = true; break; } else{ if(matrix[top + (bottom - top) / 2][matrix[0].length - 1] < target) top = top + (bottom - top) / 2 + 1; else{ top = top + (bottom - top) / 2; break; } } } if(!exists) exists = (Arrays.binarySearch(matrix[top], target) < 0) ? false : true; } return exists; } }