287. Find the Duplicate Number
Problem:
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.
Example 1:
Input: [1,3,4,2,2]
Output: 2
Example 2:
Input: [3,1,3,4,2]
Output: 3
Note:
- You must not modify the array (assume the array is read only).
- You must use only constant, O(1) extra space.
- Your runtime complexity should be less than O(n2).
- There is only one duplicate number in the array, but it could be repeated more than once.
思路:
Solution (C++):
int findDuplicate(vector<int>& nums) {
int n = nums.size(), i = 0;
for (i; i < n-1; ++i) {
for (int j = i+1; j < n; ++j) {
if (nums[i] == nums[j]) return nums[i];
}
}
return nums[i];
}
性能:
Runtime: 1388 ms Memory Usage: 7.7 MB
思路:
Solution (C++):
性能:
Runtime: ms Memory Usage: MB
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