diff --git a/PrimalityTest/c++/SEGSEIVE.CPP b/PrimalityTest/c++/SEGSEIVE.CPP new file mode 100644 index 0000000..1c38b8a --- /dev/null +++ b/PrimalityTest/c++/SEGSEIVE.CPP @@ -0,0 +1,29 @@ +// This functions finds all primes smaller than 'limit' +// using simple sieve of eratosthenes. +void simpleSieve(int limit) +{ + // Create a boolean array "mark[0..limit-1]" and + // initialize all entries of it as true. A value + // in mark[p] will finally be false if 'p' is Not + // a prime, else true. + bool mark[limit]; + memset(mark, true, sizeof(mark)); + + // One by one traverse all numbers so that their + // multiples can be marked as composite. + for (int p=2; p*p +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; +} \ No newline at end of file