chore(CPlusPlus): add max and min average (#631)

Co-authored-by: Ming Tsai <37890026+ming-tsai@users.noreply.github.com>

algorithms/CPlusPlus/Arrays/max-min-avg.cpp

@@ -0,0 +1,84 @@
+/* Finding maximum,minimum and average of an array 
+
+SAMPLE INPUT: 4
+               5
+               6
+               7
+               8
+               
+SAMPLE OUTPUT: 8
+               5
+               6
+                       */
+
+//Time complexity= O(n)
+//Space complexity= O(n)
+
+//DESCRIPTION
+//Problem related to find the maximum, minimum and average from the given array.
+
+
+#include<iostream>
+using namespace std;
+
+//function to find max element in an array
+
+int max(int *arr, int k, int size) 
+{
+    int i;
+for(i=1; i<size; i++)
+{
+    if(arr[i]>k)
+    {
+        k=arr[i];
+    }
+}
+return k;
+}
+
+//function to find min element in an array
+
+int min(int *arr, int k, int size) 
+{
+    int i;
+for(i=1; i<size; i++)
+{
+    if(arr[i]<k)
+    {
+        k=arr[i];
+    }
+}
+return k;
+}
+
+//function to find average of an array
+
+int avg(int *arr, int k, int size)  
+{
+    int sum=0,avg;
+    for(int i=0; i<size; i++)
+    {
+     sum=sum+arr[i];  //finding sum of every element in an array
+    }
+     avg=sum/size;
+     return avg;
+}
+
+int main()
+{
+    int size;
+    int k=0;
+    cout<<"Enter the size of an array\n";
+    cin>>size;
+    int *arr=new int[size];   //dynamic memory allocation 
+    cout<<"Enter elements in an array\n";
+    for (int i = 0; i < size; i++)
+    {
+        cin>>arr[i];
+    }
+    k=arr[0];
+    cout<<"Maximum element is:\n"<<max(arr,k,size)<<"\n";
+    cout<<"Minimum element is:\n"<<min(arr,k,size)<<"\n";
+    cout<<"Average will be:\n"<<avg(arr,k,size)<<"\n";
+    return 0;
+}

algorithms/CPlusPlus/README.md

@@ -29,6 +29,7 @@
 - [Merge two sorted array without using extraspace](Arrays/merge-two-sorted-array.cpp)
 - [All unique triplet that sum up to given value](Arrays/three-sum.cpp)
 - [Next permutation](Arrays/next-permutation.cpp)
+- [Maximum Minimum Average of numbers](Arrays/max-min-avg.cpp)
 
 ## Dynamic-Programming