[leetcode]287. Find the Duplicate Number
Analysis
fighting!!!—— [每天刷题并不难0.0]
Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.
Implement
(二分查找O(nlogn))
class Solution {
public:
int findDuplicate(vector<int>& nums) {
int n = nums.size();
int left = 0;
int right = n-1;
int mid;
while(left < right){
mid = (left+right)/2;
int cnt = 0;
for(auto num:nums){
if(num <= mid)
cnt++;
}
if(cnt > mid)
right = mid;
else
left = mid+1;
}
return left;
}
};