HDU4622 Reincarnation【SAM】

HDU4622 Reincarnation

给出一个串，每次询问其一个子串有多少不同的子串

按每个后缀建立\(SAM\)不断往后加字符，然后记录答案，查询的时候直接用即可

//#pragma GCC optimize("O3")
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<bits/stdc++.h>
using namespace std;
function<void(void)> ____ = [](){ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);};
const int MAXN = 4444;
int res[MAXN][MAXN];
char s[MAXN];
struct SAM{
    int len[MAXN],link[MAXN],ch[MAXN][26],ret,tot,last;
    void init(){
        memset(ch,0,sizeof(ch));
        link[tot = last = 0] = -1;
        ret = 0;
    }
    void extend(int c){
        int np = ++tot, p = last;
        len[np] = len[last] + 1;
        while(p!=-1 and !ch[p][c]){
            ch[p][c] = np;
            p = link[p];
        }
        if(p==-1) link[np] = 0;
        else{
            int q = ch[p][c];
            if(len[p]+1==len[q]) link[np] = q;
            else{
                int clone = ++tot;
                len[clone] = len[p] + 1;
                link[clone] = link[q];
                ret += len[clone] - len[link[clone]];
                memcpy(ch[clone],ch[q],sizeof(ch[q]));
                ret -= len[q] - len[link[q]];
                link[q] = link[np] = clone;
                ret += len[q] - len[link[q]];
                while(p!=-1 and ch[p][c]==q){
                    ch[p][c] = clone;
                    p = link[p];
                }
            }
        }
        last = np;
        ret += len[np] - len[link[np]];
    }
}sam;
void solve(){
    cin >> s;
    int n = strlen(s);
    for(int i = 0; i < n; i++){
        sam.init();
        for(int j = i; j < n; j++){
            sam.extend(s[j]-'a');
            res[i][j] = sam.ret;
        }
    }
    int q; cin >> q;
    while(q--){
        int l, r; cin >> l >> r;
        cout << res[l-1][r-1] << endl;
    }
}
int main(){
    ____();
    int T;
    for(cin >> T; T; T--) solve();
    return 0;
}