added kdiffpairs

Author: codenitros

october/kdiffpairs.cpp

@@ -0,0 +1,55 @@
+/*
+
+Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array.
+
+A k-diff pair is an integer pair (nums[i], nums[j]), where the following are true:
+
+0 <= i, j < nums.length
+i != j
+|nums[i] - nums[j]| == k
+Notice that |val| denotes the absolute value of val.
+
+ 
+
+Example 1:
+
+Input: nums = [3,1,4,1,5], k = 2
+Output: 2
+Explanation: There are two 2-diff pairs in the array, (1, 3) and (3, 5).
+Although we have two 1s in the input, we should only return the number of unique pairs.
+
+
+Input: nums = [1,3,1,5,4], k = 0
+Output: 1
+Explanation: There is one 0-diff pair in the array, (1, 1).
+*/
+
+//solution
+
+
+class Solution {
+public:
+    int findPairs(vector<int>& nums, int k) {
+        unordered_map<int,int> hashmap;
+        for(int i:nums){
+            hashmap[i]++;
+        }
+        
+        int res=0;
+        for(auto p:hashmap){
+            int x = p.first;
+            
+            if(hashmap.find(x+k)==hashmap.end()){
+                continue;
+            }
+            //man this is some crazy code
+            // if k=0 then we need to consider only those nums that have repeated more than once
+            // if k!=0 then for every x we need to check if x+k is in map 
+            res+=(k==0)? (hashmap[x+k]>=2) : hashmap[x+k]>=1;
+        }
+        
+        
+        return res;
+        
+    }
+};