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Find K-th Smallest Pair Distance in C++
Suppose we have an integer array; we have to find the kth smallest distance among all the pairs. The distance of a pair (A, B) is actually the absolute difference between A and B. So if the input is like [1,3,8], then all possible pairs are [1,3], [3, 8], [1, 8], then when k = 2, the second smallest distance is 5 (8 - 3).
To solve this, we will follow these steps −
- n := size of nums, x := 0
- for initialize i := 0, when i < n, update (increase i by 1), do −
- x := maximum of x and nums[i]
- Define an array cnt of size x + 1
- for initialize i := 0, when i < n, update (increase i by 1), do −
- for initialize j := i + 1, when j < n, update (increase j by 1), do −
- increase cnt[|nums[j] - nums[i]|] by 1
- for initialize j := i + 1, when j < n, update (increase j by 1), do −
- for initialize i := 0, when i <= x, update (increase i by 1), do −
- if cnt[i] >= k, then −
- return i
- k := k - cnt[i]
- if cnt[i] >= k, then −
- return x
Let us see the following implementation to get better understanding −
Example
#include <bits/stdc++.h>
using namespace std;
class Solution {
public:
int smallestDistancePair(vector<int>& nums, int k) {
int n = nums.size();
int x = 0;
for(int i = 0; i < n; i++)x = max(x, nums[i]);
vector <int> cnt(x + 1);
for(int i = 0 ; i < n; i++){
for(int j = i + 1; j < n; j++){
cnt[abs(nums[j] - nums[i])]++;
}
}
for(int i = 0; i <= x; i++){
if(cnt[i] >= k)return i;
k -= cnt[i];
}
return x;
}
};
main(){
Solution ob;
vector<int> v = {1,3,8};
cout << (ob.smallestDistancePair(v, 2));
}Input
{1,3,8}Output
5
Updated on: 02-Jun-2020
182 Views
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