POJ 2217 Secretary

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 300000;
18 int n,k,_rank[maxn],sa[maxn],lcp[maxn],tmp[maxn];
19 char ss[100010];
20 bool cmp_sa(int i,int j){
21     if(_rank[i] != _rank[j]) return _rank[i] < _rank[j];
22     int ri = i+k <= n ? _rank[i+k]:-1;
23     int rj = j+k <= n ? _rank[j+k]:-1;
24     return ri < rj;
25 }
26 void construct_sa(char *S,int *sa){
27     for(int i = 0; i <= n; i++){
28         sa[i] = i;
29         _rank[i] = i < n ? S[i]:-1;
30     }
31     for(k = 1; k <= n; k <<= 1){
32         sort(sa,sa+n+1,cmp_sa);
33         tmp[sa[0]] = 0;
34         for(int i = 1; i <= n; i++)
35             tmp[sa[i]] = tmp[sa[i-1]] + cmp_sa(sa[i-1],sa[i]);
36         for(int i = 0; i <= n; i++)
37             _rank[i] = tmp[i];
38     }
39 }
40 void construct_lcp(char *S,int *lcp){
41     for(int i = 0; i <= n; i++) _rank[sa[i]] = i;
42     int h = lcp[0] = 0;
43     for(int i = 0; i < n; i++){
44         if(h) h--;
45         for(int j = sa[_rank[i]-1]; i+h < n && j+h < n && S[i+h] == S[j+h]; ++h);
46         lcp[_rank[i]-1] = h;
47     }
48 }
49 int main() {
50     int t,slen;
51     scanf("%d",&t);
52     getchar();
53     while(t--){
54         gets(ss);
55         slen = strlen(ss);
56         ss[slen] = ‘#‘;
57         gets(ss+slen+1);
58         n = strlen(ss);
59         memset(sa,0,sizeof(sa));
60         memset(lcp,0,sizeof(lcp));
61         construct_sa(ss,sa);
62         construct_lcp(ss,lcp);
63         int ans = 0;
64         for(int i = 0; i < n; i++)
65             if((sa[i] < slen) != (sa[i+1] < slen)) ans = max(ans,lcp[i]);
66         printf("Nejdelsi spolecny retezec ma delku %d.\n",ans);
67     }
68     return 0;
69 }