442. Find All Duplicates in an Array（LeetCode）

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Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

Find all the elements that appear twice in this array.

Could you do it without extra space and in O(n) runtime?

Example:

Input:
[4,3,2,7,8,2,3,1]

Output:
[2,3]

 1 class Solution {
 2 public:
 3     vector<int> findDuplicates(vector<int>& nums) {
 4         vector<int> res;
 5         for (int i = 0; i < nums.size(); i++){
 6             nums[abs(nums[i]) - 1] = -nums[abs(nums[i]) - 1];
 7             if (nums[abs(nums[i]) - 1] > 0) res.push_back(abs(nums[i]));
 8         }
 9         return res;
10     }
11 };

442. Find All Duplicates in an Array（LeetCode）

标签：color   with   appear   run   do it   for   app   could   other   

原文地址：http://www.cnblogs.com/wujufengyun/p/7239920.html