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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.
Note:
O(n2).
public int FindDuplicate(int[] nums) { int slow = 0; int fast = 0; while(true) { slow = nums[slow]; fast = nums[nums[fast]]; if (slow == fast) break; } int t=0; while(true) { slow = nums[slow]; t = nums[t]; if (slow == t) break; } return slow; }
public int FindDuplicate(int[] nums) { int left = 1; int n = nums.Count()-1; int right = nums.Count()-1; while(left< right) { int mid = left + (right - left)/2; int sumLeft = 0; for(int i = 0 ;i< nums.Count();i++) { if(nums[i]<=mid) sumLeft++; } if(sumLeft <= mid) left = mid+1; else right = mid; } return left; }
287. Find the Duplicate Number
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原文地址：http://www.cnblogs.com/renyualbert/p/5898554.html
