poj2573

poj 2573  Wa Wa Wa  不知爲何 留個紀念

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <string>


using namespace std;

int a[1001],n;

int g(int *b,int l,int h)
{
    int i=l,j=l-1,x=b[h];
    for(;i<h;++i)
    {
        if(b[i] < x)
        {
            ++j;
            int temp = b[j];
            b[j] = b[i];
            b[i] = temp;
        }
    }
    b[h] = b[j+1];
    b[j+1] = x;
    return j+1;
}

void s(int *b,int l,int h)
{
    if(l<h)
    {
        int mid = g(b,l,h);
        s(b,l,mid-1);
        s(b,mid+1,h);
    }
}

int cross1()
{
    int sum=0,t1,t2;
    int total = n;
    while(total>=4)
    {
        t1 = a[2]+a[1]+a[total]+a[2];
        t2 = a[total]+a[1]+a[total-1]+a[1];
        if(t1<t2) sum+=t1;
        else sum+=t2;
        total-=2;
    }
    if(total == 2)
        sum += a[2];
    else
        sum += a[1]+a[2]+a[3];
    return sum;
}
void cross2()
{
    int t1,t2;
    int total = n;
    while(total>=4)
    {
        t1 = a[2]+a[1]+a[total]+a[2];
        t2 = a[total]+a[1]+a[total-1]+a[1];
        if(t1<t2) printf("%d %d\n%d\n%d %d\n%d\n",a[1],a[2],a[1],a[total-1],a[total],a[2]);
        else printf("%d %d\n%d\n%d %d\n%d\n",a[1],a[total],a[1],a[1],a[total-1],a[1]);
        total-=2;
    }
    if(total == 2)
        printf("%d %d\n",a[1],a[2]);
    else
        printf("%d %d\n%d\n%d %d\n",a[1],a[3],a[1],a[1],a[2]);
}

int main()
{
    scanf("%d",&n);
    memset(a,0,sizeof(a));
    for(int i=1;i<=n;++i)
        scanf("%d",&a[i]);
    s(a,1,n);
    printf("%d\n",cross1());
    cross2();


    return 0;
}