POJ1743---Musical Theme （后缀数组+二分）

题意 ：求最长不相交重复子串的长度。。

可以先求出LCP，，对于长度 二分出答案。。（竟然不会写二分）

 #include <set>
 #include <map>
 #include <cmath>
 #include <ctime>
 #include <queue>
 #include <stack>
 #include <cstdio>
 #include <string>
 #include <vector>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 typedef unsigned long long ull;
 typedef long long ll;
 const int inf = 0x3f3f3f3f;
 const double eps = 1e-;
 const int maxn = 2e4+;
 int sa[maxn], k, len, tmp[maxn], rank[maxn];
 int s[maxn];
 bool cmp(int i, int j)
 {
     if (rank[i] != rank[j])
         return rank[i] < rank[j];
     else
     {
         int x = (i + k <= len ? rank[i+k] : -);
         int y = (j + k <= len ? rank[j+k] : -);
         return x < y;
     }
 }
 void build_sa()
 {
     for (int i = ; i <= len; i++)
     {
         sa[i] = i;
         rank[i] = i < len ? s[i] : -;
     }
     for (k = ; k <= len; k *= )
     {
         sort (sa, sa+len+, cmp);
         tmp[sa[]] = ;
         for (int i = ; i <=  len; i++)
         {
             tmp[sa[i]] = tmp[sa[i-]] + (cmp(sa[i-], sa[i]) ?  : );
         }
         for (int i = ; i <= len; i++)
         {
             rank[i] = tmp[i];
         }
     }
 }
 int lcp[maxn];
 void Get_lcp()
 {
     for (int i = ; i < len; i++)
     {
         rank[sa[i]] = i;
     }
     int h = ;
     lcp[] = ;
     for (int i = ; i < len; i++)
     {
         int j = sa[rank[i]-];
         if (h > )
             h--;
         for (; i+h < len && j+h < len; h++)
             if (s[i+h] != s[j+h])
                 break;
         lcp[rank[i]] = h;
     }
 }
 bool check(int m)
 {
     int mini = len, maxi = ;
     for (int i = ; i <= len; i++)
     {
         if (maxi - mini >= m )
             return true;
         if (lcp[i] < m)
         {
             mini = len, maxi = ;
             continue;
         }
         mini = min(sa[i-], mini);
         maxi = max(sa[i-], maxi);
         mini = min(sa[i], mini);
         maxi = max(sa[i], maxi);
     }
     return false;
 }
 int main()
 {
     #ifndef ONLINE_JUDGE
         freopen("in.txt","r",stdin);
     #endif
     int n;
     while (scanf ("%d", &n), n)
     {
         for (int i = ; i < n; i++)
             scanf ("%d", s+i);
         for (int i = ; i < n-; i++)
             s[i] = s[i+] - s[i] + ;
         len = n-;
         build_sa();
         Get_lcp();
         int ua = , ub = len;
         int mid;
         while (ua+ < ub)
         {
             mid = (ua + ub ) >> ;
             if (check(mid) == true)
                 ua = mid;
             else
                 ub = mid;
         }
         ua = (ua <  ?  : ua + );
         printf("%d\n", ua);
     }
     return ;
 }