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658. Find K Closest Elements

中文文档

Description

Given a sorted integer array arr, two integers k and x, return the k closest integers to x in the array. The result should also be sorted in ascending order.

An integer a is closer to x than an integer b if:

  • |a - x| < |b - x|, or
  • |a - x| == |b - x| and a < b

 

Example 1:

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

Example 2:

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

 

Constraints:

  • 1 <= k <= arr.length
  • 1 <= arr.length <= 104
  • arr is sorted in ascending order.
  • -104 <= arr[i], x <= 104

Solutions

Method 1: Sort

Method 2: Binary search

Python3

class Solution:
    def findClosestElements(self, arr: List[int], k: int, x: int) -> List[int]:
        arr.sort(key=lambda v: abs(v - x))
        return sorted(arr[:k])
class Solution:
    def findClosestElements(self, arr: List[int], k: int, x: int) -> List[int]:
        l, r = 0, len(arr)
        while r - l > k:
            if x - arr[l] <= arr[r - 1] - x:
                r -= 1
            else:
                l += 1
        return arr[l: r]
class Solution:
    def findClosestElements(self, arr: List[int], k: int, x: int) -> List[int]:
        left, right = 0, len(arr) - k
        while left < right:
            mid = (left + right) >> 1
            if x - arr[mid] <= arr[mid + k] - x:
                right = mid
            else:
                left = mid + 1
        return arr[left: left + k]

Java

class Solution {
    public List<Integer> findClosestElements(int[] arr, int k, int x) {
        List<Integer> ans = Arrays.stream(arr).boxed().sorted((a, b) -> {
            int v = Math.abs(a - x) - Math.abs(b - x);
            return v == 0 ? a - b : v;
        }).collect(Collectors.toList());
        ans = ans.subList(0, k);
        Collections.sort(ans);
        return ans;
    }
}
class Solution {
    public List<Integer> findClosestElements(int[] arr, int k, int x) {
        int l = 0, r = arr.length;
        while (r - l > k) {
            if (x - arr[l] <= arr[r - 1] - x) {
                --r;
            } else {
                ++l;
            }
        }
        List<Integer> ans = new ArrayList<>();
        for (int i = l; i < r; ++i) {
            ans.add(arr[i]);
        }
        return ans;
    }
}
class Solution {
    public List<Integer> findClosestElements(int[] arr, int k, int x) {
        int left = 0;
        int right = arr.length - k;
        while (left < right) {
            int mid = (left + right) >> 1;
            if (x - arr[mid] <= arr[mid + k] - x) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        List<Integer> ans = new ArrayList<>();
        for (int i = left; i < left + k; ++i) {
            ans.add(arr[i]);
        }
        return ans;
    }
}

C++

int target;

class Solution {
public:
    static bool cmp(int& a, int& b) {
        int v = abs(a - target) - abs(b - target);
        return v == 0 ? a < b : v < 0;
    }

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

Go

func findClosestElements(arr []int, k int, x int) []int {
	sort.Slice(arr, func(i, j int) bool {
		v := abs(arr[i]-x) - abs(arr[j]-x)
		if v == 0 {
			return arr[i] < arr[j]
		}
		return v < 0
	})
	ans := arr[:k]
	sort.Ints(ans)
	return ans
}

func abs(x int) int {
	if x >= 0 {
		return x
	}
	return -x
}
func findClosestElements(arr []int, k int, x int) []int {
	l, r := 0, len(arr)
	for r-l > k {
		if x-arr[l] <= arr[r-1]-x {
			r--
		} else {
			l++
		}
	}
	return arr[l:r]
}
func findClosestElements(arr []int, k int, x int) []int {
	left, right := 0, len(arr)-k
	for left < right {
		mid := (left + right) >> 1
		if x-arr[mid] <= arr[mid+k]-x {
			right = mid
		} else {
			left = mid + 1
		}
	}
	return arr[left : left+k]
}

Rust

impl Solution {
    pub fn find_closest_elements(arr: Vec<i32>, k: i32, x: i32) -> Vec<i32> {
        let n = arr.len();
        let mut l = 0;
        let mut r = n;
        while r - l != k as usize {
            if x - arr[l] <= arr[r - 1] - x {
                r -= 1;
            } else {
                l += 1;
            }
        }
        arr[l..r].to_vec()
    }
}
impl Solution {
    pub fn find_closest_elements(arr: Vec<i32>, k: i32, x: i32) -> Vec<i32> {
        let k = k as usize;
        let n = arr.len();
        let mut left = 0;
        let mut right = n - k;
        while left < right {
            let mid = left + (right - left) / 2;
            if x - arr[mid] > arr[mid + k] - x {
                left = mid + 1;
            } else {
                right = mid;
            }
        }
        arr[left..left + k].to_vec()
    }
}

TypeScript

function findClosestElements(arr: number[], k: number, x: number): number[] {
    let l = 0;
    let r = arr.length;
    while (r - l > k) {
        if (x - arr[l] <= arr[r - 1] - x) {
            --r;
        } else {
            ++l;
        }
    }
    return arr.slice(l, r);
}
function findClosestElements(arr: number[], k: number, x: number): number[] {
    let left = 0;
    let right = arr.length - k;
    while (left < right) {
        const mid = (left + right) >> 1;
        if (x - arr[mid] <= arr[mid + k] - x) {
            right = mid;
        } else {
            left = mid + 1;
        }
    }
    return arr.slice(left, left + k);
}

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