Add Shell Sort

shell_sort.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+#include <algorithm>
+#include <array>
+
+using namespace std;
+
+int main() {
+	char arr[] = {'S', 'H', 'E', 'L', 'L', 'S', 'O', 'R', 'T', 'E', 'X', 'A', 'M', 'P', 'L', 'E'};
+	int N = sizeof(arr);
+	int h = 1;
+
+	while(h < N/3) {
+		h = 3*h + 1;
+	}
+
+	while(h >= 1) {
+		for(int i = h; i < N; i++) {
+			for(int j = i; j >= h &&  (arr[j] < arr[j-h]); j -= h) {
+				swap(arr[j], arr[j-h]);
+			}
+		}
+		h = h/3;
+	}
+
+	for(int i = 0; i < N; i++) {
+		cout << arr[i] << " -- ";
+	}
+	cout << endl;
+
+	return 0;
+}