LeetCode34: Search for a Range

LeetCode34: Search for a Range

 

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 orderO(LogN).

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].

 

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// Question requirement: Give a sorted array, find the first position of the target and the last position of the target, and find the first position of the target, index1, respectively, and the position where the target finally appears, index2 // subtract 1 from the position where (target + 1) appears for the first time to obtain the position class Solution {public: vector
 
  
SearchRange (vector
  
   
& Nums, int target) {int index1 = lower_bound (nums, target); int index2 = lower_bound (nums, target + 1)-1; // use (target + 1) subtract 1 from the first position to obtain the final position of the target if (index1 <nums. size () & nums [index1] = target) return {index1, index2}; else return {-1,-1 };} int lower_bound (vector
   
    
& Nums, int target) {int left = 0, right = nums. size ()-1; while (left <= right) {int mid = (right + left)/2; if (nums [mid] <target) left = mid + 1; else right = mid-1 ;}return left ;}};