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shell排序变体

#include 
   
    using namespace std;const int mod = 1000000007;int solve(vector
    
     & data,int l,int r){    if(l>=r-1) return 0;    int mid = (l+r+1)/2;    int ans1 = solve(data,l,mid);    int ans2 = solve(data,mid,r);    int i = l;    int j = mid;    int ans = ans1 + ans2;    while(i
     
      
        data[j]){            ans = (ans + (r-j))%mod;            i++;        }else{            j++;        }    }    sort(data.begin()+l,data.begin()+r,greater
       
        ());    return ans;}int InversePairs(vector
        
          data) { int l = data.size(); return solve(data,0,l);}int main(){ int a[] = {1,2,3,4,5,6,7,0}; vector
         
           v(a,a+8); printf("%d\n",InversePairs(v)); return 0;}
         
        
       
      
     
    
   

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