BOJ 480 田田背课文

#include <cstdio>
#include <cstring>
#include <string>
#include <iostream>

using namespace std;

const int MAX = 1000100;

void radix(int * str, int *a, int *b, int n, int m){
static int count[MAX];
memset(count,0,sizeof(count));
for(int i = 0; i < n; ++i) ++count[str[a[i]]];
for(int i = 1; i <= m; ++i) count[i] += count[i-1];
for(int i = n -1; i >= 0; --i) b[--count[str[a[i]]]] = a[i];
}

void suffix_array(int* str,int * sa, int n, int m)
{
static int rank[MAX],a[MAX],b[MAX];
for(int i = 0; i < n; ++i) rank[i] =i;
radix(str,rank,sa,n,m);

rank[sa[0]] = 0;
for(int i = 1; i < n; ++i)
rank[sa[i]]= rank[sa[i-1]] +(str[sa[i]]!=str[sa[i-1]]);
for(int i = 0; 1<<i< n; ++i){
for(int j = 0; j < n; ++j){
a[j] = rank[j]+1;
b[j] = j + (1<<i) >=n? 0: rank[j + (1<<i)] + 1;
sa[j] = j;
}
radix(b,sa,rank,n,n);
radix(a,rank,sa,n,n);
rank[sa[0]] = 0;
for(int j = 1; j < n; ++j){
rank[sa[j]] = rank[sa[j-1]] + (a[sa[j-1]] != a[sa[j]] || b[sa[j-1]] != b[sa[j]]);
}
}
}

int duplicate_substr(string str)
{
string rev;
static int s[MAX],sa[MAX],rank[MAX],h[MAX];
int n = str.length();
copy(str.begin(),str.end(),s);
suffix_array(s,sa,n,256);

for(int i = 0 ; i < n; ++i)
rank[sa[i]] = i;

int k = 0;
int ans1 =0,pos1 = 0;
for(int i = 0; i < n; ++i){
k = k==0? 0: k - 1;
while(rank[i] > 0 && s[i + k] == s[sa[rank[i] - 1] + k]) ++k;

h[rank[i]] = k;
if(h[rank[i]] > ans1){
ans1 = h[rank[i]];
pos1 = i;
}
}
return str.substr(pos1,ans1).length();
}

int main(void)
{
int T;
string str;
while(cin>>str){
cout<<duplicate_substr(str) + 1<<'\n';
}
return 0;
}