#include <iostream>
#include <vector>
#include <algorithm>


using namespace std;

 class Solution
 {
 public:
    int smallSum(vector<int>& nums)
    {
        if(nums.size()<2) return 0;
        return guibing(nums,0,nums.size()-1);
    }

 private:
    int guibing(vector<int>& nums,int L,int R)
    {
        if(L>=R) return 0;
        int mid=L+((R-L)>>1);

        return guibing(nums,L,mid)+guibing(nums,mid+1,R)+merger(nums,L,mid,R);
    }
    int merger(vector<int>& nums,int L,int mid,int R)
    {
        int result=0;
        int i=L;
        int j=mid+1;
        vector<int> help;
        while(i<=mid && j<=R)
        {
            if(nums[i]<nums[j])
            {
                result+=nums[i]*(R-j+1);
                help.push_back(nums[i++]);
            }else
            {
                help.push_back(nums[j++]);
            }
        }
        while(i<=mid)
        {
            help.push_back(nums[i++]);
        }
        while(j<=R)
        {
            help.push_back(nums[j++]);
        }
        for(int i=0;i<help.size();i++)
        {
            nums[L+i]=help[i];
        }
        return result;
    }

 };

int main()
{
    Solution ss;
    int A[]={1,3,4,2,5};
    int len=sizeof(A)/sizeof(*A);
    vector<int> nums;
    for(int i=0;i<len;i++)
    {
        nums.push_back(A[i]);
        cout<<A[i]<<" ";
    }
    cout<<endl;
    cout<<ss.smallSum(nums)<<endl;
    for(int i=0;i<nums.size();i++)
    {
        cout<<nums[i]<<" ";
    }
    cout<<endl;
    return 0;
}