34. Search for a Range

34. Search for a Range

Given an array of integers sorted in ascending order, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,
Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var searchRange = function(nums, target) {
    
    var len = nums.length;
    var start = -1,end =start;
    
    var i = 0;
    var j = len -1;
    
    
    
    while(i <= j){
        
        var mid = Math.floor((i+j)/2);
        
        if(target === nums[mid]){
           start = end = mid;
            break;
        }
        
        if(target < nums[mid]){
            
            j = mid -1;
        }else{
            
            i = mid + 1;
        }       
                
    }
    
    
    while(start - 1 >= 0 && nums[start - 1] == target){
            
            start -= 1;
            
     }
        
    while(end + 1 <= len -1 && nums[end + 1] == target){
            end += 1; 
    }
    
    
    var res = [];
    
    res.push(start);
    res.push(end);
    
    return res;
};