2016多校联合训练4 F - Substring 后缀数组

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
#include <vector>
#include <bitset>
#define ll long long
#define rep(x,to) for(int x=0;x<(to);x++)
#define repn(x,to) for(int x=1;x<=(to);x++)
#define clr(x) memset(x,0,sizeof(x))
#define pli pair<ll, int>
#define MEMSET(x,v) memset(x,v,sizeof(x))
#define pll pair<ll,ll>
#define pb push_back
#define MP make_pair
using namespace std;
const int N = 5e5 + 100;
int t1[N], t2[N], c[N];

bool cmp(int *r, int a, int b, int l) {
    return r[a] == r[b] && r[a+l] == r[b+l];
}
void da(int str[], int sa[], int Rank[], int heigh[], int n, int m) {
    n++;
    int i, j, p, *x = t1, *y = t2;
    for(i = 0; i < m; ++i) c[i] = 0;
    for(i = 0; i < n; ++i) c[ x[i] = str[i] ]++;
    for(i = 1; i < m; ++i) c[i] += c[i - 1];
    for(i = n - 1; i >= 0; --i) sa[ --c[ x[i] ] ] = i;

    for(j = 1; j <= n; j <<= 1) {

        p = 0;
        for(i = n - j; i < n; ++i) y[p++] = i;
        for(i = 0; i < n; ++i) if(sa[i] >= j) y[p++] = sa[i] - j;

        for(i = 0; i < m; ++i) c[i] = 0;
        for(i = 0; i < n; ++i) c[ x[ y[i] ] ]++;
        for(i = 1; i < m; ++i) c[i] += c[i - 1];
        for(i = n - 1; i >=0; --i) sa[ --c[ x[ y[i] ] ] ] = y[i];
        swap(x, y);
        p = 1;
        x[ sa[0] ] = 0;
        for(i = 1; i < n; ++i) x[ sa[i] ] = cmp(y, sa[i - 1], sa[i], j) ? p - 1: p++;
        if(p >= n) break;
        m = p;
    }
    int k = 0;
    n--;
    for(i = 0; i <= n; ++i) Rank[ sa[i] ] = i;
    for(i = 0; i < n; ++i) {
        if(k) k--;
        j = sa[ Rank[i] - 1 ];
        while(str[i + k] == str[j + k]) k++;
        heigh[ Rank[i] ] = k;
    }
}

int Rank[N], heigh[N];
char str[N];
int r[N];
int sa[N];
char X[12];
int pre[N];
int pos[N];
int _ = 1;

void solve(int n) {
    memset(pos, 0, sizeof pos);
    int p = -1;
    ll sum = 0, num = 0;
    for(int i = n - 1; i >= 0; --i) {
        if(str[i] == X[0]) p = i;
        pos[i] = p;
        if(pos[i] != -1) sum += (n - pos[i]);
    }
    //for(int i = 0; i < n; ++i) printf("%d ", pos[i]);

    for(int i = 2; i <= n; ++i) {

        if(pos[ sa[i - 1] ] == -1 || pos[ sa[i] ] == -1) continue;
        int c1 = pos[ sa[i - 1] ] - sa[i - 1] + 1;
        int c2 = pos[ sa[i] ] - sa[i] + 1;
        int h = heigh[i];
        if(c1 > h || c2 > h) continue;
        num += (h - c1 + 1);
    }
    printf("Case #%d: %I64d\n", _++, sum - num);
}
int main()
{
#ifdef LOCAL
    freopen("in", "r", stdin);
#endif
    int cas; scanf("%d", &cas);
    while(cas --) {
        scanf("%s%s", X, str);
        int n = strlen(str);
        for(int i = 0; i < n; ++i) r[i] = str[i];
        r[n] = 0;
        da(r, sa, Rank, heigh, n, 128);


        solve(n);
       // for(int i = 0; i < n; ++i) printf("%d ", Rank[i]); puts("");
       // for(int i = 1; i <= n; ++i) printf("%d ", sa[i]); puts("");
       // for(int i = 2; i <= n; ++i) printf("%d ", heigh[i]); puts("");
    }
    return 0;
}