思维题 Corrupted Images

The goal of the game is to reach the n^th box starting from the 1^st box, by jumping between the boxes. The player can do one of the following jumps:

1. Jump one box to the right.
2. If the player stands at a box of color x, he/she can jump to the closest box of color x that is to the right of him, if such box exist.   

Input

3
6
9 2 4 7 1 5
5
1 2 1 1 4
6
1 2 3 1 3 2

Output

5
3
2

可以一步一步地跳，也可以一步跳到与当前石头数字一样的石头上（仅能跳到第一个相同数字的石头）。

#include<bits/stdc++.h>
using namespace std;

int n,T,a[200005],x,look[200005],ans[200005];
int main()
{
   scanf("%d",&T);
   while(T--)
   {
       memset(look,-1,sizeof(look));
       scanf("%d",&n);
       for(int i=1;i<=n;i++)
            scanf("%d",&a[i]);
        ans[1]=0;
        look[a[1]]=0;
        for(int i=2;i<=n;i++)
           {
               if(look[a[i]]!=-1)
               {
                   ans[i]=min(ans[i-1]+1,look[a[i]]+1);
                   look[a[i]]=ans[i];
               }
               else
               {
                   ans[i]=ans[i-1]+1;
                   look[a[i]]=ans[i];
               }
           }
           printf("%d\n",ans[n]);
   }
}

当前状态可能是上一个石头跳过来的，也可能是上一个数字相同石头跳过来的。look[a[i]]!=-1,代表之前出现过a[i],look[a[i]]记录的是走到前一状态上一个相同数字的步数。