Leetcode 2364 Count Number of Bad Pairs Solution in Java | Hindi Coding Community

 

You are given a 0-indexed integer array nums. A pair of indices (i, j) is a bad pair if i < j and j - i != nums[j] - nums[i].

Return the total number of bad pairs in nums.

 

Example 1:

Input: nums = [4,1,3,3]
Output: 5
Explanation: The pair (0, 1) is a bad pair since 1 - 0 != 1 - 4.
The pair (0, 2) is a bad pair since 2 - 0 != 3 - 4, 2 != -1.
The pair (0, 3) is a bad pair since 3 - 0 != 3 - 4, 3 != -1.
The pair (1, 2) is a bad pair since 2 - 1 != 3 - 1, 1 != 2.
The pair (2, 3) is a bad pair since 3 - 2 != 3 - 3, 1 != 0.
There are a total of 5 bad pairs, so we return 5.

Example 2:

Input: nums = [1,2,3,4,5]
Output: 0
Explanation: There are no bad pairs.

 

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109

Java Code :

class Solution {

public long countBadPairs(int[] nums) {

long ans=0L;

int len=nums.length;

for(int i=0;i<len;i++)

nums[i]-=i;

HashMap<Integer,Integer> freq=new HashMap<>();

for(int num:nums) {

freq.put(num,freq.getOrDefault(num,0)+1);

}

for(int key:freq.keySet()) {

if(freq.get(key)>1) {

long value=freq.get(key);

ans+=((value*1L*(value-1L))/2L);

}

}

long length=len;

long total=((length*1L*(length-1L))/2L);

return total-ans;

}

}