LeetCode - Search in Rotated Sorted Array

22 Jan 2018 • LeetCode(Second)

Question Definition

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Java Solution

public int search(int[] nums, int target) {
    int low = 0;
    int high = nums.length - 1;
    while(low <= high){
        int mid = (low + high) / 2;
        if(nums[mid] == target) return mid;
        if((nums[mid] < nums[high] && target > nums[mid] && target <= nums[high])
           ||(nums[mid] > nums[high] && (target > nums[mid] || target < nums[low]))
           ){
            while(mid < nums.length - 1 && nums[mid + 1] == nums[mid]) mid++;
            low = mid + 1;
        }else{
            while(mid > 0 && nums[mid - 1] == nums[mid]) mid--;
            high = mid - 1;
        }
    }
    return -1;
}

LeetCode - Search a 2D Matrix

22 Jan 2018 • LeetCode(Second)

Question Definition

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.
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