【HDOJ】2890 Longest Repeated subsequence

后缀数组的应用。和男人八题那个后缀数组差不多。

/* 2890 */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int maxn = 50050;
int a[maxn], b[maxn], aa[maxn];
int pos[maxn], pn;
int rrank[maxn], height[maxn], sa[maxn];
int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
int n, k, at;

bool cmp(int *r, int a, int b, int l) {
    return r[a]==r[b] && r[a+l]==r[b+l];
}

void da(int *r, int *sa, int n, int m) {
    int i, j, *x=wa, *y=wb, *t, p;
    
    for (i=0; i<m; ++i) wc[i] = 0;
    for (i=0; i<n; ++i) wc[x[i]=r[i]]++;
    for (i=1; i<m; ++i) wc[i] += wc[i-1];
    for (i=n-1; i>=0; --i) sa[--wc[x[i]]] = i;
    for (j=1,p=1; p<n; j*=2, m=p) {
        for (p=0,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<n; ++i) wv[i] = x[y[i]];
        for (i=0; i<m; ++i) wc[i] = 0;
        for (i=0; i<n; ++i) wc[wv[i]]++;
        for (i=1; i<m; ++i) wc[i] += wc[i-1];
        for (i=n-1; i>=0; --i) sa[--wc[wv[i]]] = y[i];
        for (t=x, x=y, y=t, i=1,p=1,x[sa[0]]=0; i<n; ++i)
            x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1:p++;
    }
}

void calheight(int *r, int *sa, int n) {
    int i, j, k=0;
    
    for (i=1; i<=n; ++i) rrank[sa[i]] = i;
    for (i=0; i<n; height[rrank[i++]]=k)
    for (k?k--:0, j=sa[rrank[i]-1]; r[i+k]==r[j+k]; ++k);
}

bool judge(int bound) {
    int i = 1;
    int pn = 0;
    
    while (i <= n) {
        if (height[i] < bound) {
            at = sa[i-1];
            sort(pos, pos+pn);
            int kk = 1, p = pos[0];
            rep(j, 1, pn) {
                if (pos[j]-p >= bound) {
                    p = pos[j];
                    ++kk;
                }
            }
            
            if (kk >= k)
                return true;
            pn = 0;
            pos[pn++] = sa[i++];
        } else {
            pos[pn++] = sa[i++];
        }
    }
    at = sa[n-1];
    sort(pos, pos+pn);
    int kk = 1, p = pos[0];
    rep(j, 1, pn) {
        if (pos[j]-p >= bound) {
            p = pos[j];
            ++kk;
        }
    }
    
    if (kk >= k)
        return true;
    
    return false;
}

void printSa(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", sa[i]);
    putchar('
');
}

void printHeight(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", height[i]);
    putchar('
');
}

void solve() {
    sort(b, b+n);
    int nn = unique(b, b+n) - b;
    
    rep(i, 0, n)
        aa[i] = lower_bound(b, b+nn, a[i]) - b + 1;
    aa[n] = 0;
    
    da(aa, sa, n+1, nn+4);
    calheight(aa, sa, n);
    
    #ifndef ONLINE_JUDGE
        // printSa(n);
        // printHeight(n);
    #endif
    
    int l = 1, r = n, mid;
    int ans = 0, fr;
    
    while (l <= r) {
        mid = (l + r) >> 1;
        if (judge(mid)) {
            ans = mid;
            fr = at;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    
    printf("%d
", ans);
    rep(i, 0, ans)
        printf("%d
", b[aa[fr+i]-1]);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int t;
    
    scanf("%d", &t);
    while (t--) {
        scanf("%d %d", &n, &k);
        rep(i, 0, n) {
            scanf("%d", &a[i]);
            b[i] = a[i];
        }
        solve();
        if (t)
            putchar('
');
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}