poj 3270 Cow Sorting（置换）

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给你一个序列，让你通过交换变成升序，每次交换的花费是两个元素之和
对于一个置换，就两种变换的方法，要么就是把置换里最小的数字和边上的数字换
要么就是和外面的最小的交换

代码：

#include <map>#include <set>#include <stack>#include <queue>#include <cmath>#include <string>#include <vector>#include <cstdio>#include <cctype>#include <cstring>#include <sstream>#include <cstdlib>#include <iostream>#include <algorithm>#pragma comment(linker,"/STACK:102400000,102400000")using namespace std;#define   MAX           10005#define   MAXN          1000005#define   maxnode       205#define   sigma_size    2#define   lson          l,m,rt<<1#define   rson          m+1,r,rt<<1|1#define   lrt           rt<<1#define   rrt           rt<<1|1#define   middle        int m=(r+l)>>1#define   LL            long long#define   ull           unsigned long long#define   mem(x,v)      memset(x,v,sizeof(x))#define   lowbit(x)     (x&-x)#define   pii           pair<int,int>#define   bits(a)       __builtin_popcount(a)#define   mk            make_pair#define   limit         10000//const int    prime = 999983;const int    INF   = 0x3f3f3f3f;const LL     INFF  = 0x3f3f;//const double pi    = acos(-1.0);const double inf   = 1e18;const double eps   = 1e-9;const LL     mod   = 1e9+7;const ull    mx    = 133333331;/*****************************************************/inline void RI(int &x) {      char c;      while((c=getchar())<'0' || c>'9');      x=c-'0';      while((c=getchar())>='0' && c<='9') x=(x<<3)+(x<<1)+c-'0'; }/*****************************************************/vector<int> v[MAX];int a[MAX];int b[MAX];int c[MAX];int vis[MAX*10];int main(){    //freopen("in.txt","r",stdin);    int n;    cin>>n;    mem(vis,0);    int cnt=0;    for(int i=1;i<=n;i++){        scanf("%d",&a[i]);        b[i]=a[i];        c[i]=a[i];        v[0].push_back(a[i]);    }    sort(b+1,b+n+1);    sort(v[0].begin(),v[0].end());    for(int i=1;i<=n;i++){        int pos=lower_bound(b+1,b+n+1,a[i])-b;        c[i]=pos;    }    for(int i=1;i<=n;i++){        if(!vis[c[i]]){            ++cnt;            v[cnt].push_back(b[c[i]]);            vis[c[i]]=1;            int k=c[c[i]];            while(k!=c[i]){                vis[k]=1;                v[cnt].push_back(b[k]);                k=c[k];            }            sort(v[cnt].begin(),v[cnt].end());        }    }    LL ans=0;    for(int i=1;i<=cnt;i++){        LL mini=1e18;        LL sum=0;        if(v[i].size()==1) continue;        for(int j=0;j<v[i].size();j++){            sum+=v[i][j];        }        sum+=v[i][0]*(v[i].size()-2);        mini=min(sum,mini);        if(v[0][0]<v[i][0]){            sum=0;            for(int j=1;j<v[i].size();j++) sum+=v[i][j];            sum+=(v[i].size()+1)*v[0][0]+2*v[i][0];        }        mini=min(sum,mini);        ans+=mini;    }    cout<<ans<<endl;    return 0;}

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