HDU 4455 Substrings

第37届ACM/ICPC杭州现场赛C题

DP经典。

思路：

#include<stdio.h>
#include<iostream>
using namespace std;

#include<math.h>
#include<algorithm>

#define repA(p,q,i)  for(int (i)=(p); (i)!=(q); ++(i) )
#define repD(p,q,i)  for(int (i)=(p); (i)!=(q); --(i) )
#define repAE(p,q,i)  for(int (i)=(p); (i)<=(q); ++(i) )
#define repDE(p,q,i)  for(int (i)=(p); (i)>=(q); --(i) )
#define range 1000010

int a[range];
int loc[range];
int dis[range];
int last[range];
long long query[range];
int n;

int main()
{
    while(scanf("%d",&n) != EOF)
    {
        if(n==0)  break;
        repAE(1,n,i)
          scanf("%d",&a[i]);
        repA(0,range,i)
          dis[i]=loc[i]=0;
        repAE(1,n,i)
        {
            ++dis[i - loc[ a[i] ] ] ;
            loc[a[i] ] = i ;
        }

        repA(0,range,i)
          loc[i] = 0;
        last[0]=0;
        repAE(1,n,i)
        {
            if( loc[a[n-i+1] ] == 0 )
            {
                last[i]=last[i-1] + 1;
                loc[a[n-i+1] ]=1;
            }
            else
                last[i]=last[i-1];
        }
        
        query[0]=0;
        int num=n;
        repAE(1,n,i)
        {
            num -= dis[i-1];
            query[i] = query[i-1] + num ;
            query[i] -= last[i-1];
        }

        int q,id;
        scanf("%d",&q);
        while(q--)
        {
            scanf("%d",&id);
            cout<<query[id]<<endl;
        }
    }
    return 0;
}