SPOJ 220 后缀数组

简略题意：每个字符串中至少出现两次，且不重叠的最长子串

先将$n$个字符串连接起来，二分答案$t$，用$t$分组之后看同一组的是否出现在所有串中至少两次，且在每个原串中的最大最小$sa[i]-sa[j]>=k$。其实只要同时存在最大最小位置，即出现了至少两次。

#include <iostream>
#include <cstring>
#include <map>
#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

const int N = 1e5+1100;

int n, q;
char str[N], str2[N];
int belong[N];
int f = 0;
int minv;

namespace SA {
    int sa[N], rank[N], height[N], s[N<<1], t[N<<1], p[N], cnt[N], cur[N];
    #define pushS(x) sa[cur[s[x]]--] = x
    #define pushL(x) sa[cur[s[x]]++] = x
    #define inducedSort(v) fill_n(sa, n, -1); fill_n(cnt, m, 0);                  \
        for (int i = 0; i < n; i++) cnt[s[i]]++;                                  \
        for (int i = 1; i < m; i++) cnt[i] += cnt[i-1];                           \
        for (int i = 0; i < m; i++) cur[i] = cnt[i]-1;                            \
        for (int i = n1-1; ~i; i--) pushS(v[i]);                                  \
        for (int i = 1; i < m; i++) cur[i] = cnt[i-1];                            \
        for (int i = 0; i < n; i++) if (sa[i] > 0 &&  t[sa[i]-1]) pushL(sa[i]-1); \
        for (int i = 0; i < m; i++) cur[i] = cnt[i]-1;                            \
        for (int i = n-1;  ~i; i--) if (sa[i] > 0 && !t[sa[i]-1]) pushS(sa[i]-1)
    void sais(int n, int m, int *s, int *t, int *p) {
        int n1 = t[n-1] = 0, ch = rank[0] = -1, *s1 = s+n;
        for (int i = n-2; ~i; i--) t[i] = s[i] == s[i+1] ? t[i+1] : s[i] > s[i+1];
        for (int i = 1; i < n; i++) rank[i] = t[i-1] && !t[i] ? (p[n1] = i, n1++) : -1;
        inducedSort(p);
        for (int i = 0, x, y; i < n; i++) if (~(x = rank[sa[i]])) {
            if (ch < 1 || p[x+1] - p[x] != p[y+1] - p[y]) ch++;
            else for (int j = p[x], k = p[y]; j <= p[x+1]; j++, k++)
                if ((s[j]<<1|t[j]) != (s[k]<<1|t[k])) {ch++; break;}
            s1[y = x] = ch;
        }
        if (ch+1 < n1) sais(n1, ch+1, s1, t+n, p+n1);
        else for (int i = 0; i < n1; i++) sa[s1[i]] = i;
        for (int i = 0; i < n1; i++) s1[i] = p[sa[i]];
        inducedSort(s1);
    }
    template<typename T>
    int mapCharToInt(int n, const T *str) {
        int m = *max_element(str, str+n);
        fill_n(rank, m+1, 0);
        for (int i = 0; i < n; i++) rank[str[i]] = 1;
        for (int i = 0; i < m; i++) rank[i+1] += rank[i];
        for (int i = 0; i < n; i++) s[i] = rank[str[i]] - 1;
        return rank[m];
    }
    template<typename T>
    void suffixArray(int n, const T *str) {
        int m = mapCharToInt(++n, str);
        sais(n, m, s, t, p);
        for (int i = 0; i < n; i++) rank[sa[i]] = i;
        for (int i = 0, h = height[0] = 0; i < n-1; i++) {
            int j = sa[rank[i]-1];
            while (i+h < n && j+h < n && s[i+h] == s[j+h]) h++;
            if (height[rank[i]] = h) h--;
        }
    }
    template <typename T>
    void init(T *str){
        str[n] = 0;
        suffixArray(n, str);
    }
    int mx[12], mi[12];
    int vis[12], count = 0;
    void checkinit() {
        memset(mx, 0, sizeof mx);
        memset(mi, 0x3f3f3f3f, sizeof mi);
        memset(vis, 0, sizeof vis);
        count = 0;
    }
    bool check(int x) {
        checkinit();
        for(int i =  1; i <= n; i++) {
            if(height[i] >= x) {
                int pos = sa[i] + 1;
                int bl = belong[sa[i]];
                if(mx[bl] < pos) mx[bl] = pos;
                if(mi[bl] > pos) mi[bl] = pos;
                if(mx[bl] - mi[bl] >= x)
                    if(!vis[bl]) vis[bl] = 1, count++;
                if(count == q)
                    return 1;
                } else {
                    checkinit();
                    int pos = sa[i] + 1;
                    int bl = belong[sa[i]];
                    if(mx[bl] < pos) mx[bl] = pos;
                    if(mi[bl] > pos) mi[bl] = pos;
                    if(mx[bl] - mi[bl] >= x)
                        if(!vis[bl]) vis[bl] = 1, count++;
                }
        }
        return 0;
    }
    void solve() {
        int l = 0, r = minv + 1, m;
        while(l < r) {
            m = (l + r) >> 1;
            if(check(m)) l = m + 1;
            else r = m;
        }
        printf("%d\n", l - 1);
    }
};

int t;

int main() {
    scanf("%d", &t);
    while(t--) {
        scanf("%d", &q);
        int s = 0;
        int d = 1;
        minv = 0x3f3f3f3f;
        for(int i = 1; i <= q; i++) {
            scanf("%s", str2);
            int len = strlen(str2);
            for(int j = 0; j < len; j++) str[s+j] = str2[j], belong[s+j] = i;
            s += len;
            minv = min(minv, len);
            str[s] = d;
            d++;
            s++;
        }
        n = s;
        SA::init(str);
        SA::solve();
    }
    return 0;
}