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| 1 | +#include<iostream> |
| 2 | +using namespace std; |
| 3 | + |
| 4 | +// A utility function to get maximum value in arr[] |
| 5 | +int getMax(int arr[], int n) |
| 6 | +{ |
| 7 | + int mx = arr[0]; |
| 8 | + for (int i = 1; i < n; i++) |
| 9 | + if (arr[i] > mx) |
| 10 | + mx = arr[i]; |
| 11 | + return mx; |
| 12 | +} |
| 13 | + |
| 14 | +// A function to do counting sort of arr[] according to |
| 15 | +// the digit represented by exp. |
| 16 | +void countSort(int arr[], int n, int exp) |
| 17 | +{ |
| 18 | + int output[n]; // output array |
| 19 | + int i, count[10] = {0}; |
| 20 | + |
| 21 | + // Store count of occurrences in count[] |
| 22 | + for (i = 0; i < n; i++) |
| 23 | + count[ (arr[i]/exp)%10 ]++; |
| 24 | + |
| 25 | + // Change count[i] so that count[i] now contains actual |
| 26 | + // position of this digit in output[] |
| 27 | + for (i = 1; i < 10; i++) |
| 28 | + count[i] += count[i - 1]; |
| 29 | + |
| 30 | + // Build the output array |
| 31 | + for (i = n - 1; i >= 0; i--) |
| 32 | + { |
| 33 | + output[count[ (arr[i]/exp)%10 ] - 1] = arr[i]; |
| 34 | + count[ (arr[i]/exp)%10 ]--; |
| 35 | + } |
| 36 | + |
| 37 | + // Copy the output array to arr[], so that arr[] now |
| 38 | + // contains sorted numbers according to current digit |
| 39 | + for (i = 0; i < n; i++) |
| 40 | + arr[i] = output[i]; |
| 41 | +} |
| 42 | + |
| 43 | +// The main function to that sorts arr[] of size n using |
| 44 | +// Radix Sort |
| 45 | +void radixsort(int arr[], int n) |
| 46 | +{ |
| 47 | + // Find the maximum number to know number of digits |
| 48 | + int m = getMax(arr, n); |
| 49 | + |
| 50 | + // Do counting sort for every digit. Note that instead |
| 51 | + // of passing digit number, exp is passed. exp is 10^i |
| 52 | + // where i is current digit number |
| 53 | + for (int exp = 1; m/exp > 0; exp *= 10) |
| 54 | + countSort(arr, n, exp); |
| 55 | +} |
| 56 | + |
| 57 | + |
| 58 | +void print(int arr[], int n) |
| 59 | +{ |
| 60 | + for (int i = 0; i < n; i++) |
| 61 | + cout << arr[i] << " "; |
| 62 | +} |
| 63 | + |
| 64 | +// Driver program to test above functions |
| 65 | +int main() |
| 66 | +{ |
| 67 | + int n; |
| 68 | + cout<<"\n Size : "; |
| 69 | + cin>>n; |
| 70 | + |
| 71 | + int arr[n]; |
| 72 | + cout<<"\n Enter values in array : "; |
| 73 | + for(int i=0;i<n;i++) |
| 74 | + cin>>arr[i]; |
| 75 | + |
| 76 | + radixsort(arr, n); |
| 77 | + print(arr, n); |
| 78 | + return 0; |
| 79 | +} |
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