HDU4622: Reincarnation

Posted 2020-10-31 Cyhlnj

题面

给定一个串，每次询问\(l~r\)组成的子串的不同子串个数
串长\(2000\)

Sol

每个左端点建一个\(sam\)同时记录答案

# include <bits/stdc++.h>
# define IL inline
# define RG register
# define Fill(a, b) memset(a, b, sizeof(a))
# define File(a) freopen(a".in", "r", stdin), freopen(a".out", "w", stdout)
using namespace std;
typedef long long ll;

IL int Input(){
    RG int x = 0, z = 1; RG char c = getchar();
    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
    return x * z;
}

const int maxn(4005);

int tot = 1, last = 1, trans[26][maxn], fa[maxn], len[maxn], n, ans[maxn][maxn];
char s[maxn];

IL void Extend(RG int c){
    RG int p = last, np = ++tot; last = tot;
    len[np] = len[p] + 1;
    while(p && !trans[c][p]) trans[c][p] = np, p = fa[p];
    if(!p) fa[np] = 1;
    else{
        RG int q = trans[c][p];
        if(len[q] == len[p] + 1) fa[np] = q;
        else{
            RG int nq = ++tot;
            len[nq] = len[p] + 1, fa[nq] = fa[q];
            for(RG int i = 0; i < 26; ++i) trans[i][nq] = trans[i][q];
            fa[np] = fa[q] = nq;
            while(p && trans[c][p] == q) trans[c][p] = nq, p = fa[p];
        }
    }
}

int main(RG int argc, RG char* argv[]){
    for(RG int T = Input(); T; --T){
        scanf(" %s", s + 1), n = strlen(s + 1);
        for(RG int l = 1; l <= n; ++l){
            Fill(fa, 0), Fill(len, 0), Fill(trans, 0), tot = last = 1;
            for(RG int r = l; r <= n; ++r){
                Extend(s[r] - 'a' + 1);
                ans[l][r] = ans[l][r - 1] + len[last] - len[fa[last]];
            }
        }
        for(RG int Q = Input(); Q; --Q){
            RG int l = Input(), r = Input();
            printf("%d\n", ans[l][r]);
        }
    }
    return 0;
}