LeetCode -- Search in Rotated Sorted Array, rotatedsortedarray

LeetCode -- Search in Rotated Sorted Array, rotatedsortedarray
Search in Rotated Sorted Array:

Most of the questions you search online are incorrect.
As follows:
Use while (first! = Last) this loop,
-1.
When we do this first = last, it will jump out of the loop and cause an error.
The correct method should be do {} while (first! = Last ).

Ideas:

The array is as follows: Large -- small -- medium

Boundaries are divided into four situations:

Left <mid: whether the key is in (left, mid). If it is in, right = mid-1; if not, left = mid + 1; left> mid: whether the key is in (mid, right). If the key is in, left = mid + 1; if not, right = mid-1;

Efficiency:

Time complexity O (log n), space complexity O (1)

C code

#include <iostream>using namespace std;int search(int* nums, int numsSize, int target) {    int left = 0;    int right = numsSize-1;    do{        int mid = (left+right)/2;        if(nums[mid]==target) return mid;        if(nums[left]<=nums[mid]){            if(nums[left]<=target && target<nums[mid]){                right = mid-1;            }else{                left = mid+1;            }        } else {            if(nums[mid]<target && target<=nums[right]){                left = mid+1;            }else{                right = mid-1;            }        }    }while(left<=right);            return -1;}int main(int argc, char *argv[]) {    int arr[] = {3,1,2};    int result = search(arr,3,2);    printf("%d", result);    return 0;}

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