Anjan Dutta

Leet Code 704: Binary Search

Problem statement:

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

You must write an algorithm with O(log n) runtime complexity.

Constraints:

1 <= nums.length <= 104
-104 < nums[i], target < 104
All the integers in nums are unique.
nums is sorted in ascending order.

Solution:

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var search = function(nums, target) {
    
    const len = nums.length;
    
    let start = 0;
    let end = len -1;
    
    while (start <= end) {
        let mid = parseInt((start+end)/2);
        if(nums[mid]===target) {
            return mid;
        } else if(target < nums[mid]) {
            end = mid -1;
        } else {
            start = mid+1;
        }
    }
    
    return -1;
    
};