Merge pull request #331 from cheehwatang/add-2006-CountNumberOfPairsWithAbsoluteDifferenceK

cheehwatang · web-flow · commit f17a3a9e5672 · 2023-09-10T21:34:07.000+08:00
Add 2006. Count Number of Pairs With Absolute Difference K
diff --git a/README.md b/README.md
@@ -27,6 +27,17 @@
     <th>Solution</th>
     <th>Topics</th>
   </tr>
+  <tr>
+    <td align="center">September 10th</td>
+    <td>2006. <a href="https://leetcode.com/problems/count-number-of-pairs-with-absolute-difference-k/">Count Number of Pairs With Absolute Difference K</a></td>
+    <td align="center">$\text{\color{TealBlue}Easy}$</td>
+    <td align="center">
+      <a href="https://github.com/cheehwatang/leetcode-java/blob/main/solutions/2006.%20Count%20Number%20of%20Pairs%20With%20Absolute%20Difference%20K/CountNumberOfPairsWithAbsoluteDifferenceK.java">Brute Force</a>
+    </td>
+    <td align="center">
+      <a href="#array">Array</a>
+    </td>
+  </tr>
   <tr>
     <td align="center">September 9th</td>
     <td>2028. <a href="https://leetcode.com/problems/find-missing-observations/">Find Missing Observations</a></td>
@@ -75,18 +86,6 @@
       <a href="#memoization">Memoization</a>
     </td>
   </tr>
-  <tr>
-    <td align="center">September 5th</td>
-    <td>1137. <a href="https://leetcode.com/problems/n-th-tribonacci-number/">N-th Tribonacci Number</a></td>
-    <td align="center">$\text{\color{TealBlue}Easy}$</td>
-    <td align="center">
-      <a href="https://github.com/cheehwatang/leetcode-java/blob/main/solutions/1137.%20N-th%20Tribonacci%20Number/NthTribonacciNumber_Iterative.java">Dynamic Programming</a>
-    </td>
-    <td align="center">
-      <a href="#dynamic-programming">Dynamic Programming</a>,
-      <a href="#math">Math</a>
-    </td>
-  </tr>
 </table>
 </br>
 <hr>
@@ -1563,6 +1562,18 @@
       <a href="https://github.com/cheehwatang/leetcode-java/blob/main/solutions/1995.%20Count%20Special%20Quadruplets/CountSpecialQuadruplets_HashTable.java"><em>Hash Table</em></a>
     </td>
   </tr>
+  <tr>
+    <td align="center">2006</td>
+    <td><a href="https://leetcode.com/problems/count-number-of-pairs-with-absolute-difference-k/">Count Number of Pairs With Absolute Difference K</a></td>
+    <td align="center">
+      <a href="https://github.com/cheehwatang/leetcode-java/blob/main/solutions/2006.%20Count%20Number%20of%20Pairs%20With%20Absolute%20Difference%20K/CountNumberOfPairsWithAbsoluteDifferenceK.java">Java</a>
+    </td>
+    <td align="center">$\text{\color{TealBlue}Easy}$</td>
+    <td align="center">
+      <a href="#array">Array</a>
+    </td>
+    <td></td>
+  </tr>
   <tr>
     <td align="center">2007</td>
     <td><a href="https://leetcode.com/problems/find-original-array-from-doubled-array/">Find Original Array From Doubled Array</a></td>
diff --git a/solutions/2006. Count Number of Pairs With Absolute Difference K/CountNumberOfPairsWithAbsoluteDifferenceK.java b/solutions/2006. Count Number of Pairs With Absolute Difference K/CountNumberOfPairsWithAbsoluteDifferenceK.java
@@ -0,0 +1,24 @@
+package com.cheehwatang.leetcode;
+
+// Time Complexity  : O(n^2),
+// where 'n' is the length of 'nums'.
+// We traverse 'nums' in a nested for-loop to count the pair with 'k' differences.
+//
+// Space Complexity : O(1),
+// as the auxiliary space used is independent of the input.
+
+public class CountNumberOfPairsWithAbsoluteDifferenceK {
+
+    // Approach:
+    // Intuitive and brute force approach to check every combination and count the ones with 'k' difference.
+
+    public int countKDifference(int[] nums, int k) {
+        int count = 0;
+        for (int i = 0; i < nums.length - 1; i++) {
+            for (int j = i + 1; j < nums.length; j++) {
+                if (Math.abs(nums[i] - nums[j]) == k) count++;
+            }
+        }
+        return count;
+    }
+}
