Create Radix sort in c++ (#366)

Author: aishalxgupta

CPP/sorting/Radix sort in c++

@@ -0,0 +1,73 @@
+#include <bits/stdc++.h>
+using namespace std;
+ 
+// A utility function to get maximum value in arr[]
+int getMax(int arr[], int n)
+{
+    int mx = arr[0];
+    for (int i = 1; i < n; i++)
+        if (arr[i] > mx)
+            mx = arr[i];
+    return mx;
+}
+ 
+// A function to do counting sort of arr[] according to
+// the digit represented by exp.
+void countSort(int arr[], int n, int exp)
+{
+    int output[n]; // output array
+    int i, count[10] = { 0 };
+ 
+    // Store count of occurrences in count[]
+    for (i = 0; i < n; i++)
+        count[(arr[i] / exp) % 10]++;
+ 
+    // Change count[i] so that count[i] now contains actual
+    //  position of this digit in output[]
+    for (i = 1; i < 10; i++)
+        count[i] += count[i - 1];
+ 
+    // Build the output array
+    for (i = n - 1; i >= 0; i--) {
+        output[count[(arr[i] / exp) % 10] - 1] = arr[i];
+        count[(arr[i] / exp) % 10]--;
+    }
+ 
+    // Copy the output array to arr[], so that arr[] now
+    // contains sorted numbers according to current digit
+    for (i = 0; i < n; i++)
+        arr[i] = output[i];
+}
+ 
+// The main function to that sorts arr[] of size n using
+// Radix Sort
+void radixsort(int arr[], int n)
+{
+    // Find the maximum number to know number of digits
+    int m = getMax(arr, n);
+ 
+    // Do counting sort for every digit. Note that instead
+    // of passing digit number, exp is passed. exp is 10^i
+    // where i is current digit number
+    for (int exp = 1; m / exp > 0; exp *= 10)
+        countSort(arr, n, exp);
+}
+ 
+// A utility function to print an array
+void print(int arr[], int n)
+{
+    for (int i = 0; i < n; i++)
+        cout << arr[i] << " ";
+}
+ 
+// Driver Code
+int main()
+{
+    int arr[] = { 170, 45, 75, 90, 802, 24, 2, 66 };
+    int n = sizeof(arr) / sizeof(arr[0]);
+     
+      // Function Call
+      radixsort(arr, n);
+    print(arr, n);
+    return 0;
+}