# [LeetCode] 658. Find K Closest Elements 寻找K个最近元素

Given a sorted array, two integers k and x, find the k closest elements to x in the array. The result should also be sorted in ascending order. If there is a tie, the smaller elements are always preferred.

Example 1:

Input: [1,2,3,4,5], k=4, x=3
Output: [1,2,3,4]


Example 2:

Input: [1,2,3,4,5], k=4, x=-1
Output: [1,2,3,4]


Note:

1. The value k is positive and will always be smaller than the length of the sorted array.
2. Length of the given array is positive and will not exceed 104
3. Absolute value of elements in the array and x will not exceed 104

class Solution {
public:
vector<int> findClosestElements(vector<int>& arr, int k, int x) {
vector<int> res = arr;
while (res.size() > k) {
if (x - res.front() <= res.back() - x) {
res.pop_back();
} else {
res.erase(res.begin());
}
}
return res;
}
};

class Solution {
public:
vector<int> findClosestElements(vector<int>& arr, int k, int x) {
int left = 0, right = arr.size() - k;
while (left < right) {
int mid = left + (right - left) / 2;
if (x - arr[mid] > arr[mid + k] - x) left = mid + 1;
else right = mid;
}
return vector<int>(arr.begin() + left, arr.begin() + left + k);
}
};

Github 同步地址：

https://github.com/grandyang/leetcode/issues/658

Find K-th Smallest Pair Distance

https://leetcode.com/problems/find-k-closest-elements/

https://leetcode.com/problems/find-k-closest-elements/discuss/106419/O(log-n)-Java-1-line-O(log(n)-%2B-k)-Ruby

https://leetcode.com/problems/find-k-closest-elements/discuss/202785/Very-simple-Java-O(n)-solution-using-two-pointers

https://leetcode.com/problems/find-k-closest-elements/discuss/106426/JavaC%2B%2BPython-Binary-Search-O(log(N-K)-%2B-K)

LeetCode All in One 题目讲解汇总(持续更新中...)

posted @ 2017-09-14 10:42  Grandyang  阅读(16303)  评论(11编辑  收藏  举报