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[LeetCode] Find Minimum in Rotated Sorted Array 二分搜索

Suppose a sorted array 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).

Find the minimum element.

You may assume no duplicate exists in the array.

 

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 Array Binary Search
 

  二分查找的变形,比较神奇的是数列可能没有旋转,查找前判断下数列旋转了没有便可以应对。
 
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#include <iostream>#include <vector>using namespace std;class Solution {public:    int findMin(vector<int> &num) {        int n = num.size();        if(n<2||num[0]<num[n-1]) return num[0];        int lft=0,rgt=n-1,mid=n-1;        while(lft+1<rgt){            if(num[mid-1]>num[mid]) break;            mid = (lft+ rgt)/2;            cout<<lft<<" "<<mid<<" "<<rgt<<endl;            if(num[lft]<num[mid])   lft=mid;            else    rgt=mid;            mid = rgt;        }        return num[mid];    }};int main(){    vector<int> num{3,4,5,6,1,2};    Solution sol;    cout<<sol.findMin(num)<<endl;    return 0;}
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[LeetCode] Find Minimum in Rotated Sorted Array 二分搜索