【xjoi】Game（SAM，SG函数）

#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10, M = 5e5 + 10, E = 25;
namespace SAM
{
const int PN = N<<1, S = 26;
int last, cnt, fa[PN][E], ch[PN][26], len[PN];
void reset(){
last = cnt = 1;
}
void Copy(int x, int y){
for (int i = 0; i < S; ++ i){
ch[y][i] = ch[x][i];
}
fa[y][0] = fa[x][0];
}
int insert(char c){
c -= 'a';
int p = last, np = ++cnt;
last = np;
len[np] = len[p]+1;
while (p && !ch[p][c]){
ch[p][c] = np, p = fa[p][0];
}
if (p == 0) fa[np][0] = 1;
else{
int q = ch[p][c];
if (len[q] == len[p]+1) fa[np][0] = q;
else{
int nq = ++cnt;
Copy(q, nq);
len[nq] = len[p]+1;
fa[q][0] = fa[np][0] = nq;
while (p && ch[p][c] == q){
ch[p][c] = nq, p = fa[p][0];
}
}
}
return np;
}
}
using namespace SAM;
string s;
int sn, n, q[M][2], dp[PN], pos[N];
bool tmp[S+1];
int ton[N], id[PN];

void fake_sort()
{
for (int i = 1; i <= cnt; ++ i) ton[len[i]]++;
for (int i = 1; i <= sn; ++ i) ton[i] += ton[i-1];
for (int i = cnt; i >= 1; -- i) id[ton[len[i]]--] = i;
}

void get_dp_and_fa()
{
for (int ii = cnt; ii >= 1; -- ii){
int i = id[ii];
memset(tmp, 0, sizeof(tmp));
for (int j = 0; j < S; ++ j)
if (ch[i][j]){
tmp[dp[ch[i][j]]] = 1;
}
for (int j = 0; j <= S; ++ j)
if (tmp[j] == 0){
dp[i] = j;
break;
}
}
for (int ii = 1; ii <= cnt; ++ ii){
int i = id[ii];
for (int j = 1; j < E; ++ j)
fa[i][j] = fa[fa[i][j-1]][j-1];
}
}

int get_u(int u, int _len)
{
for (int i = E-1; i >= 0; -- i)
if (len[fa[u][i]] >= _len)
u = fa[u][i];
return u;
}

void solve1()
{
int ans = 0, maxx = 0, cnt = 0;
for (int i = 1; i <= n; ++ i){
int l = q[i][0]-1, r = q[i][1]-1;
int u = get_u(pos[r], r-l+1);
ans ^= dp[u];
if (dp[u] == 1) ++ cnt;
maxx = max(maxx, dp[u]);
puts(ans ? "Fir" : "Sec");
if (maxx <= 1 && cnt % 2 == 0) puts("Fir");
else if (maxx > 1 && ans != 0) puts("Fir");
else puts("Sec");
}
}

int main()
{
ios::sync_with_stdio(false);
cin >> s >> n;
sn = s.size(http://www.amjmh.com/v/);
for (int i = 1; i <= n; ++ i)
cin >> q[i][0] >> q[i][1];
reset();
for (int i = 0; i < sn; ++ i)
pos[i] = insert(s[i]);
fake_sort();
get_dp_and_fa();
solve1();
return 0;
}