81. Search in Rotated Sorted Array II

旋转数组搜索

最新推荐文章于 2023-11-12 22:36:10 发布

转载最新推荐文章于 2023-11-12 22:36:10 发布 · 109 阅读

本文介绍了一种在未知旋转点的升序数组中查找特定目标值的方法。该数组可能包含重复元素，通过一种高效的算法实现搜索功能。

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

Write a function to determine if a given target is in the array.

The array may contain duplicates.

class Solution {
public: 
    bool search(vector<int>& nums, int target) {
        int l = 0, r = nums.size() - 1;
        while (l <= r) {
            while (l < r && nums[l] == nums[l + 1]) l++; // skip duplicates from the left
            while (r > l && nums[r] == nums[r - 1]) r--; // skip duplicates from the right
            int mid = (l + r) / 2;
            if (nums[mid] == target) return true; 
            if (nums[mid] > target) {
                if (nums[l] <= target || nums[mid] < nums[l]) r = mid - 1;
                else l = mid + 1;
            }
            else {
                if (nums[l] > target || nums[mid] >= nums[l]) l = mid + 1;
                else r = mid - 1;
            }
        } 
        return false;
    }
};