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【LeetCode】Search in Rotated Sorted Array II (2 solutions)

时间:2014-12-06 19:32:52      阅读:173      评论:0      收藏:0      [点我收藏+]

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Search in Rotated Sorted Array II

Follow up for "Search in Rotated Sorted Array":
What if duplicates are allowed?

Would this affect the run-time complexity? How and why?

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

 

解法一:顺序查找

class Solution {
public:
    bool search(int A[], int n, int target) {
        for(int i = 0; i < n; i ++)
        {
            if(A[i] == target)
                return true;
        }
        return false;
    }
};

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解法二:二分查找

关键点在于,如果mid元素与low或者high元素相同,则删除一个low或者high

class Solution {

public:
    bool search(int A[], int n, int target) {
        int low = 0;
        int high = n-1;
        while (low <= high)
        {
            int mid = (low+high)/2;
            if(A[mid] == target) 
                return true;
            if (A[low] < A[mid])
            {
                if(A[low] <= target && target < A[mid])
                //binary search in sorted A[low~mid-1]
                    high = mid - 1;
                else
                //subproblem from low to high
                    low = mid + 1;
            }
            else if(A[mid] < A[high])
            {
                if(A[mid] < target && target <= A[high])
                //binary search in sorted A[mid+1~high]
                    low = mid + 1;
                else
                //subproblem from low to mid-1
                    high = mid - 1;
            }
            else if(A[low] == A[mid])
                low += 1;    //A[low]==A[mid] is not the target, so remove it
            else if(A[mid] == A[high])
                high -= 1;  //A[high]==A[mid] is not the target, so remove it
        }
        return false;
    }
};

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【LeetCode】Search in Rotated Sorted Array II (2 solutions)

标签:style   blog   http   io   ar   color   sp   for   strong   

原文地址:http://www.cnblogs.com/ganganloveu/p/4148573.html

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