【POJ】3294 Life Forms

后缀数组。

/* 3294 */
#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 maxl = 1005;
const int maxs = 105;
const int maxn = maxl * maxs;
char s[maxs][maxl];
int id[maxn], pos[maxn], pn;
bool visit[maxs];
int a[maxn];
int rank[maxn], height[maxn], sa[maxn];
int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
int ns, ns_;

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, x[sa[0]]=0, p=1, i=1; 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) rank[sa[i]] = i;
    for (i=0; i<n; height[rank[i++]]=k)
    for (k?k--:0, j=sa[rank[i]-1]; r[j+k]==r[i+k]; ++k) ;
}

bool check(int b, int e) {
    int cnt = 0;
    
    memset(visit, false, sizeof(visit));
    rep(i, b, e+1) {
        if (!visit[id[sa[i]]]) {
            visit[id[sa[i]]] = true;
            ++cnt;
        }
    }
    
    return cnt > ns_;
}

bool judge(int bound, int n) {
    bool ret = false;
    int b, e;
    
    b = e = 0;
    rep(i, 1, n+1) {
        if (height[i] >= bound) {
            e = i;
        } else {
            if (check(b, e)) {
                if (!ret)
                    pn = 0;
                ret = true;
                pos[pn++] = sa[b];
            }
            b = e = i;
        }    
    }
    if (check(b, e)) {
        if (!ret)
            pn = 0;
        ret = true;
        pos[pn++] = sa[b];
    }
    
    return ret;
}

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() {
    int n = 0, ml = 0;
    
    if (ns == 1) {
        puts(s[0]);
        return ;
    }
    
    rep(i, 0, ns) {
        for (int j=0; ; ++j) {
            if (s[i][j] == '') {
                ml = max(ml, j);
                break;
            }
            id[n] = i;
            a[n] = s[i][j] - 'a' + 100;
            ++n;
        }
        id[n] = a[n] = i;
        ++n;
    }
    
    --n;
    da(a, sa, n+1, 130);
    calheight(a, sa, n);
    
    #ifndef ONLINE_JUDGE
        // printSa(n);
        // printHeight(n);
        // printf("ml = %d
", ml);
    #endif
    
    int l = 1, r = ml, mid;
    int ans = 0;
    ns_ = ns >> 1;
    
    while (l <= r) {
        mid = (l + r) >> 1;
        if (judge(mid, n)) {
            ans = mid;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    
    if (ans == 0) {
        puts("?");
        return ;
    }
    
    char ch;
    
    rep(i, 0, pn) {
        rep(j, 0, ans) {
            ch = a[pos[i]+j] - 100 + 'a';
            putchar(ch);
        }
        putchar('
');
    }
}

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

数据生成器。

from random import randint, shuffle
import shutil
import string


def GenDataIn():
    with open("data.in", "w") as fout:
        t = 20
        bound = 10**3
        lc = list(string.lowercase)
        for tt in xrange(t):
            n = randint(1, 10)
            fout.write("%d
" % (n))
            for i in xrange(n):
                length = randint(20, 50)
                line = ""
                for j in xrange(length):
                    idx = randint(0, 25)
                    line += lc[idx]
                fout.write("%s
" % (line))
        fout.write("0
")
        
                
def MovDataIn():
    desFileName = "F:eclipse_prjworkspacehdojdata.in"
    shutil.copyfile("data.in", desFileName)

    
if __name__ == "__main__":
    GenDataIn()
    MovDataIn()