[POJ] 3320 Jessica's Reading Problem (尺取法)

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<string.h>
 4 #include<algorithm>
 5 #include<math.h>
 6 #include<stdbool.h>
 7 #include<time.h>
 8 #include<stdlib.h>
 9 #include<set>
10 #include<map>
11 #include<stack>
12 #include<queue>
13 #include<vector>
14 using namespace std;
15 #define clr(x,y)    memset(x,y,sizeof(x))
16 #define sqr(x)      ((x)*(x))
17 #define rep(i,a,b)  for(int i=(a);i<=(b);i++)
18 #define LL          long long
19 #define INF         0x3f3f3f3f
20 #define A           first
21 #define B           second
22 const int N=1e6+131;
23 int n,p,a[N];
24 
25 void solve()
26 {
27     set<int>all;
28     map<int,int>count;
29     
30     scanf("%d",&p);
31     for(int i=0;i<p;i++) {
32         scanf("%d",&a[i]);
33         all.insert(a[i]);
34     }
35     n=all.size();
36     
37     int lb=0,ub=0,num=0;
38     int res=p;
39     while(true) {
40         while(ub<p && num<n) {
41             if(count[a[ub++]]++ == 0)
42             num++;
43         }
44         if(num<n) break;
45         res=min(res,ub-lb);
46         if(--count[a[lb++]]==0) {
47             num--;
48         }
49     }
50     
51     printf("%d\n",res);
52     
53 }
54 int main()
55 {
56     solve();
57     return 0;
58 }