标签：discus length bsp not int problem class case 第k大
Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.
For example,
Given [3,2,1,5,6,4] and k = 2, return 5.
Note:
You may assume k is always valid, 1 ? k ? array‘s length.
Credits:
Special thanks to @mithmatt for adding this problem and creating all test cases.
思路：
利用快排划分的思想来找。注意从小到大排序以后，第k大的是num[n-k]。
int partion (vector<int>& nums,int begin,int end) { int pivot = nums[begin]; while(begin<end) { while(nums[end]>=pivot && begin<end)end--; nums[begin] = nums[end]; while(nums[begin]<=pivot && begin<end)begin++; nums[end] = nums[begin]; } nums[begin] = pivot; return begin; } int findKthLargest(vector<int>& nums, int k) { int begin =0,end = nums.size()-1,n =nums.size(); while(begin<end) { int j = partion(nums,begin,end); if(j==n-k)break; else if(j<n-k)begin = j+1; else end = j-1; } return nums[n-k]; }
[leetcode-215-Kth Largest Element in an Array]
标签：discus length bsp not int problem class case 第k大
原文地址：http://www.cnblogs.com/hellowooorld/p/7435910.html
