457. 经典二分查找问题

[1, 2, 2, 4, 5, 5]

2

5

6

class Solution {
public:
/*
* @param nums: An integer array sorted in ascending order
* @param target: An integer
* @return: An integer
*/

int binarySearch(vector<int> &nums,int target,int first,int last){
while(first<last){
int mid=(first+last)/2;
if(nums[mid]==target)
return mid;
else if(nums[mid]>target)
return binarySearch(nums,target,first,mid-1);
else
return binarySearch(nums,target,mid+1,last);
}

return -1;

}
int findPosition(vector<int> &nums, int target) {
// write your code here
int first=0,last=nums.size()-1;
return binarySearch(nums,target,first,last);
}

};