Merge pull request #1 from ritika99/add-radixsort

added radixtsort

radixsort.cpp

@@ -0,0 +1,72 @@
+#include<iostream> 
+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 program to test above functions 
+int main() 
+{ 
+    int arr[] = {170, 45, 75, 90, 802, 24, 2, 66}; 
+    int n = sizeof(arr)/sizeof(arr[0]); 
+    radixsort(arr, n); 
+    print(arr, n); 
+    return 0; 
+}