leetcode/array/704. Binary Search at master · llka/leetcode · GitHub

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/*

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.


Example 1:

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

*/

class Solution {
    public int search(int[] nums, int target) {
        int leftIdx = 0;
        int rightIdx = nums.length - 1;
        while (leftIdx <= rightIdx) {
            int middleIdx = leftIdx + (rightIdx - leftIdx) / 2;

            if (nums[middleIdx] == target) {
                return middleIdx;
            }

            if (target < nums[middleIdx]) {
                rightIdx = middleIdx - 1;
            } else {
                leftIdx = middleIdx + 1;
            }
        }
        return -1;
    }
}