SDUT 3402 数据结构实验之排序五：归并求逆序数

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坑坑坑，超时，过，傻傻分不清

#include <bits/stdc++.h>using namespace std;int n;long long num;int pp[100010], tmp[100010];void Msort(int l, int r);void Merge( int l, int e,int m, int r);int main(){    num = 0;    cin >> n;    for(int i = 0; i < n; i++)    {        scanf("%d", &pp[i]);    }    Msort(0, n-1);    printf("%lld\n",num);    return 0;}void Msort(int l, int r){    if(l < r)    {        int mid = (l+r)/2;        Msort(l, mid);        Msort(mid+1, r);        Merge(l, mid, mid+1, r);    }}void Merge(int l, int e, int m, int r){    int s1 = l, s2 = m;    int k = 0;    while(s1 <= e && s2 <= r)    {        if(pp[s1] <= pp[s2])        {            tmp[k++] = pp[s1++];        }        else        {            tmp[k++] = pp[s2++];            num += e-s1+1;        }    }    while(s1 <= e)    {        tmp[k++] = pp[s1++];    }    while(s2 <= r)    {        tmp[k++] = pp[s2++];    }    /*for(int i = 0; i < r-l+1; i++,r--)    {     pp[r] = tmp[r];    }*/    for(int i=l;i<=r;i++)    {        pp[i]=tmp[i-l];    }}

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