Problem
Given a sorted array of integers, 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].
Example
Given [5, 7, 7, 8, 8, 10] and target value 8, return [3, 4].
JavaScript Code
function searchRange(nums, target) { if(nums == null || nums.length == 0){ return null; } var arr = []; arr[0] = -1; arr[1] = -1; binarySearch(nums, 0, nums.length-1, target, arr); return arr; } function binarySearch(nums, left, right, target, arr){ if(right<left) return; if(nums[left]==nums[right] && nums[left]==target){ arr[0]=left; arr[1]=right; return; } var mid = left+ parseInt((right-left)/2); if(nums[mid]<target){ binarySearch(nums, mid+1, right, target, arr); }else if(nums[mid]>target){ binarySearch(nums, left, mid-1, target, arr); }else{ arr[0]=mid; arr[1]=mid; //handle duplicates - left var t1 = mid; while(t1 >left && nums[t1]==nums[t1-1]){ t1--; arr[0]=t1; } //handle duplicates - right var t2 = mid; while(t2 < right&& nums[t2]==nums[t2+1]){ t2++; arr[1]=t2; } return; } } console.log(searchRange([2,2,2,3,4,4,8,8,8,9], 8));
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