LeetCode34. Search for a Range

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本文详细解析了LeetCode第34题“查找给定目标值的起始和结束位置”的解决方案。采用二分查找法高效寻找有序整数数组中特定目标值的位置范围，并附带实现代码。

LeetCode34. Search for a Range

题目：

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].

题目分析：

用二分查找法，用一个little和high记录查询。

代码：

class Solution {
public:
	vector<int> searchRange(vector<int>& nums, int target) {
        if (nums.size()==0) return {-1,-1};
		int mid = nums.size() / 2, high = nums.size() -1, little = 0;
		vector<int> result = { -1,-1 };
		while (little < high) {
			mid = (high + little) / 2;
			if (nums[mid] < target) little = mid + 1;
			else high = mid;
		}
		if (nums[little] != target) return result;
		else result[0] = little;
		high = nums.size() - 1;
		while (little < high) {
			mid = (high + little) / 2 + 1;
			if (nums[mid] > target) high = mid - 1;
			else little = mid;
		}
		result[1] = high;
		return result;
	}
};