add-algorithm-that-counts-the-occurences-of-numbers

algorithms/CPlusPlus/Arrays/number-occurences-counter.cpp

@@ -0,0 +1,31 @@
+/*
+Counts the occurence of each number in the given array outputs it. 
+Using an unordered_map to store the count of each number. 
+Time complexity O(n) 
+*/
+
+
+
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+void countOccurrences(const std::vector<int>& arr){
+    std::unordered_map<int, int> count;
+
+    for(int n: arr){
+        count[n]++;
+    }
+
+    for(const auto& pair : count){
+        std::cout << "The number: " << pair.first<< " occurs " <<pair.second<< " times." << std::endl;
+    }
+}
+
+int main() {
+
+    std::vector<int> myArray = {12, 4, 12, 23, 1, 1, 12, 4, 5};
+    countOccurrences(myArray);
+
+    return 0;
+}