Pairs with sum in an array

Author: mandliya

sort_search_problems/find_pairs_with_sum.cpp

@@ -0,0 +1,31 @@
+#include <bits/stdc++.h>
+
+
+void printPairWithSum(const std::vector<int>& arr, const int sum)
+{
+    std::unordered_map<int, int> hashMap;
+    bool found = false;
+    for (unsigned int i = 0; i < arr.size(); ++i)
+    {
+        // We need to check if pair(arr[i], sum-arr[i]) already
+        // exists in the map
+        //
+        if (hashMap.find(sum-arr[i]) != hashMap.end())
+        {
+            std::cout << "Found pair with sum: " << sum
+                << " with values (" << sum-arr[i] << " ," << arr[i]
+                << ") at indices (" <<  hashMap[sum-arr[i]] << " ,"
+                << i << ")" << std::endl;
+            found = true;
+        }
+        hashMap[arr[i]] = i;
+    }
+    if (!found) std::cout << "Pair not found\n";
+}
+
+int main()
+{
+    std::vector<int> arr {8, 7, 2, 5, 3, 1};
+    printPairWithSum(arr, 10);
+    return 0;
+}