LeetCode Weekly Contest 56 Find K-th Smallest Pair Distance
2017-10-31 09:54
465 查看
题目
Given an integer array, return the k-th smallest distance among all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B.Example 1:
Input:
nums = [1,3,1]
k = 1
Output: 0
Explanation:
Here are all the pairs:
(1,3) -> 2
(1,1) -> 0
(3,1) -> 2
Then the 1st smallest distance pair is (1,1), and its distance is 0.
Note:
2 <= len(nums) <= 10000.
0 <= nums[i] < 1000000.
1 <= k <= len(nums) * (len(nums) - 1) / 2.
分析
这题做题时看出二分了, 十分可惜,没想到是两次二分,回头看了第一名代码ac现在来分析题目
看到题目时 ,我先用native 算法 n平方的试试了,超时了
接着我们容易观察到
答案的范围时[最小差,最大差]
并且 观察 答案是有递增性的
这里离目标很近了接下来是判断有多少个小于中间值
这里又来了一次二分
我们会排序数组
然后二分查找
找出 差《= mid 的数
代码
class Solution { public: int f(vector<int>& a, int m) { int res = 0; for(int i = 0; i < a.size(); i++) { res += (upper_bound(a.begin(), a.end(), a[i] + m) - (a.begin() + i + 1)); } return res; } int smallestDistancePair(vector<int>& nums, int k) { sort( nums.begin() , nums.end() ); int left =0 ; int right = nums.back() - nums[0]; while( left <= right ){ int mid = ( right -left ) / 2 + left ; if( f( nums, mid ) >= k ) right = mid -1 ; else left = mid + 1 ; } return left ; } };
时间复杂度 O(N∗logN∗logM)
这里分析一下答案的二分用的时间复杂度是log(最大差(M))接着是数组的O(n)*log(n)
空间复杂度O(1)
相关文章推荐
- LEETCODE: 719 Find K-th Smallest Pair Distance
- 算法第15周Find K-th Smallest Pair Distance[hard]
- 719. Find K-th Smallest Pair Distance
- Find K-th Smallest Pair Distance:查找数组元素中差值第K大的两个元素的差值
- LWC 56:719. Find K-th Smallest Pair Distance
- leetcode 719. Find K-th Smallest Pair Distance
- leetcode 719. Find K-th Smallest Pair Distance 第k小的绝对距离 + 暴力计算真棒
- LeetCode719. Find K-th Smallest Pair Distance (hard)
- 719. Find K-th Smallest Pair Distance
- LeetCode Weekly Contest 13-TotalHamming Distance【中】
- Leet 4000 Code Find K-th Smallest Pair Distance
- 719. Find K-th Smallest Pair Distance
- leetcode 786. K-th Smallest Prime Fraction
- LeetCode Weekly Contest 40解题思路
- LeetCode Weekly Contest 48解题思路
- LeetCode Weekly Contest 8 第八周周赛
- LeetCode 786. K-th Smallest Prime Fraction
- 【LeetCode Weekly Contest 26 Q3】Friend Circles
- LeetCode Weekly Contest 51
- [LeetCode] K-th Smallest in Lexicographical Order 字典顺序的第K小数字