后缀数组 倍增算法

/*
后缀数组
倍增法
sa[i]表示从字符串sa[i]开始的后缀数组，排列第i
S[sa[i]]<S[sa[i+1]]

ran[i]表示从i下标开始的后缀数组，从小到大排列的名次
*/
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>
#include<cmath>
using namespace std;
typedef long long LL;
const int maxn = 10000+10;
int sa[maxn];
int tmp[maxn];
int ran[maxn];
int n, k;

bool cmp(const int& i,const int& j) {
if(ran[i] != ran[j])
return ran[i]<ran[j];
else {
int ri = i+k<=n?ran[i+k]:-1;
int rj = j+k<=n?ran[j+k]:-1;
return ri<rj;
}
}

void construct_sa(string s) {
n = (int)s.size();
for (int i=0; i<=n; i++) {
sa[i] = i;
ran[i] = i==n?-1:s[i];
}

for (k=1; k<=n; k*=2) {
sort(sa, sa+n+1, cmp);
tmp[sa[0]] = 0;
for (int i=1; i<=n; i++)
tmp[sa[i]] = tmp[sa[i-1]]+(cmp(sa[i-1], sa[i])?1:0);

for (int i=0; i<=n; i++)
ran[i] = tmp[i];
}
}

int main() {
string s;
cin>>s;
construct_sa(s);
return 0;
}