链接:https://leetcode-cn.com/problems/binary-search/https://leetcode-cn.com/problems/binary-search/
这题是二分查找的板子。
class Solution {
public:
int search(vector<int>& arr, int target) {
int n=arr.size();
int l=0,r=n-1;
while(l<=r){
int mid=l+(r-l)/2;
int num=arr[mid];
if(num>target){
r=mid-1;
}else if(num==target){
return mid;
}
else{
l=mid+1;
}
}
return -1;
}
};