From 6ae726e425830863bf8c50ad8738c3f68d70dc70 Mon Sep 17 00:00:00 2001
From: Hao Chen <haoel@hotmail.com>
Date: Tue, 27 Apr 2021 20:18:58 +0800
Subject: [PATCH] New Problem Solution - "1726. Tuple with Same Product"

---
 README.md                                     |  1 +
 .../TupleWithSameProduct.cpp                  | 61 +++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 algorithms/cpp/tupleWithSameProduct/TupleWithSameProduct.cpp

diff --git a/README.md b/README.md
index d848cbf30..762dfd825 100644
--- a/README.md
+++ b/README.md
@@ -87,6 +87,7 @@ LeetCode
 |1734|[Decode XORed Permutation](https://leetcode.com/problems/decode-xored-permutation/) | [C++](./algorithms/cpp/decodeXORedPermutation/DecodeXoredPermutation.cpp)|Medium|
 |1733|[Minimum Number of People to Teach](https://leetcode.com/problems/minimum-number-of-people-to-teach/) | [C++](./algorithms/cpp/minimumNumberOfPeopleToTeach/MinimumNumberOfPeopleToTeach.cpp)|Medium|
 |1732|[Find the Highest Altitude](https://leetcode.com/problems/find-the-highest-altitude/) | [C++](./algorithms/cpp/findTheHighestAltitude/FindTheHighestAltitude.cpp)|Easy|
+|1726|[Tuple with Same Product](https://leetcode.com/problems/tuple-with-same-product/) | [C++](./algorithms/cpp/tupleWithSameProduct/TupleWithSameProduct.cpp)|Medium|
 |1725|[Number Of Rectangles That Can Form The Largest Square](https://leetcode.com/problems/number-of-rectangles-that-can-form-the-largest-square/) | [C++](./algorithms/cpp/numberOfRectanglesThatCanFormTheLargestSquare/NumberOfRectanglesThatCanFormTheLargestSquare.cpp)|Easy|
 |1718|[Construct the Lexicographically Largest Valid Sequence](https://leetcode.com/problems/construct-the-lexicographically-largest-valid-sequence/) | [C++](./algorithms/cpp/constructTheLexicographicallyLargestValidSequence/ConstructTheLexicographicallyLargestValidSequence.cpp)|Medium|
 |1717|[Maximum Score From Removing Substrings](https://leetcode.com/problems/maximum-score-from-removing-substrings/) | [C++](./algorithms/cpp/maximumScoreFromRemovingSubstrings/MaximumScoreFromRemovingSubstrings.cpp)|Medium|
diff --git a/algorithms/cpp/tupleWithSameProduct/TupleWithSameProduct.cpp b/algorithms/cpp/tupleWithSameProduct/TupleWithSameProduct.cpp
new file mode 100644
index 000000000..10ca073af
--- /dev/null
+++ b/algorithms/cpp/tupleWithSameProduct/TupleWithSameProduct.cpp
@@ -0,0 +1,61 @@
+// Source : https://leetcode.com/problems/tuple-with-same-product/
+// Author : Hao Chen
+// Date   : 2021-04-27
+
+/***************************************************************************************************** 
+ *
+ * Given an array nums of distinct positive integers, return the number of tuples (a, b, c, d) such 
+ * that a * b = c * d where a, b, c, and d are elements of nums, and a != b != c != d.
+ * 
+ * Example 1:
+ * 
+ * Input: nums = [2,3,4,6]
+ * Output: 8
+ * Explanation: There are 8 valid tuples:
+ * (2,6,3,4) , (2,6,4,3) , (6,2,3,4) , (6,2,4,3)
+ * (3,4,2,6) , (4,3,2,6) , (3,4,6,2) , (4,3,6,2)
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [1,2,4,5,10]
+ * Output: 16
+ * Explanation: There are 16 valids tuples:
+ * (1,10,2,5) , (1,10,5,2) , (10,1,2,5) , (10,1,5,2)
+ * (2,5,1,10) , (2,5,10,1) , (5,2,1,10) , (5,2,10,1)
+ * (2,10,4,5) , (2,10,5,4) , (10,2,4,5) , (10,2,4,5)
+ * (4,5,2,10) , (4,5,10,2) , (5,4,2,10) , (5,4,10,2)
+ * 
+ * Example 3:
+ * 
+ * Input: nums = [2,3,4,6,8,12]
+ * Output: 40
+ * 
+ * Example 4:
+ * 
+ * Input: nums = [2,3,5,7]
+ * Output: 0
+ * 
+ * Constraints:
+ * 
+ * 	1 <= nums.length <= 1000
+ * 	1 <= nums[i] <= 10^4
+ * 	All elements in nums are distinct.
+ ******************************************************************************************************/
+
+class Solution {
+public:
+    int tupleSameProduct(vector<int>& nums) {
+        unordered_map<int, int> stat;
+        for(int i = 0; i < nums.size(); i++) {
+            for ( int j = i+1; j < nums.size(); j++) {
+                stat[nums[i]*nums[j]]++;
+            }
+        }
+        
+        int result = 0;
+        for ( auto [n, cnt] : stat) {
+            if (cnt > 1) result += cnt*2 * (cnt-1)*2;
+        }
+        return result;
+    }
+};