uva 11572 唯一的雪花

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cmath>
 5 #include<cstdlib>
 6 #include<cstring>
 7 #include<queue>
 8 #include<vector>
 9 #define inf 2147483611
10 #define ll long long
11 #define MAXN 1010101
12 #define MOD
13 using namespace std;
14 inline ll read()
15 {
16     ll x=0,f=1;
17     char ch;ch=getchar();
18     while(!isdigit(ch)) {if(ch==‘-‘) f=-1;ch=getchar();}
19     while(isdigit(ch)) {x=x*10+ch-‘0‘;ch=getchar();}
20     return x*f;
21 }
22 int l,r,ans,n,a[MAXN],hash[MAXN];
23 int main()
24 {
25     n=read();
26     l=r=1;
27     for(int i=1;i<=n;i++) a[i]=read();
28     while(r<n)
29     {
30         while(r<n)
31         {
32             if(!hash[a[r+1]]) hash[a[r++]]++;
33             else break;
34         }
35         ans=max(ans,r-l+1);
36         while(hash[a[r+1]]) {hash[a[l++]]--;}
37     }
38     printf("%d",ans);
39 }