[C++]希爾排序法

#include <iostream>

using namespace std;

int main()
{
    int arr[] = {45,84,77,83,55,49,91,64,91,5,37,31,70,38,51};
    int gap[] = {5,2,1};
    int len = size(arr);
    int current_gap;
    for(int i=0; i<3; i++){
    	current_gap = gap[i];
        for(int j=current_gap; j<len; j++){
        	int t = arr[j];
            int k = j;
            while(k>=0 && k-current_gap>=0 && arr[k-current_gap]>t){
            	arr[k] = arr[k-current_gap];
                k -= current_gap;
            }
            arr[k] = t;
        }
    }
    for(auto l : arr) cout<<l<<" ";
}

size()只有在C++17以上才能用。