后缀数组。
1 /* 3294 */
2 #include <iostream>
3 #include <sstream>
4 #include <string>
5 #include <map>
6 #include <queue>
7 #include <set>
8 #include <stack>
9 #include <vector>
10 #include <deque>
11 #include <algorithm>
12 #include <cstdio>
13 #include <cmath>
14 #include <ctime>
15 #include <cstring>
16 #include <climits>
17 #include <cctype>
18 #include <cassert>
19 #include <functional>
20 #include <iterator>
21 #include <iomanip>
22 using namespace std;
23 //#pragma comment(linker,"/STACK:102400000,1024000")
24
25 #define sti set<int>
26 #define stpii set<pair<int, int> >
27 #define mpii map<int,int>
28 #define vi vector<int>
29 #define pii pair<int,int>
30 #define vpii vector<pair<int,int> >
31 #define rep(i, a, n) for (int i=a;i<n;++i)
32 #define per(i, a, n) for (int i=n-1;i>=a;--i)
33 #define clr clear
34 #define pb push_back
35 #define mp make_pair
36 #define fir first
37 #define sec second
38 #define all(x) (x).begin(),(x).end()
39 #define SZ(x) ((int)(x).size())
40 #define lson l, mid, rt<<1
41 #define rson mid+1, r, rt<<1|1
42
43 const int maxl = 1005;
44 const int maxs = 105;
45 const int maxn = maxl * maxs;
46 char s[maxs][maxl];
47 int id[maxn], pos[maxn], pn;
48 bool visit[maxs];
49 int a[maxn];
50 int rank[maxn], height[maxn], sa[maxn];
51 int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
52 int ns, ns_;
53
54 bool cmp(int *r, int a, int b, int l) {
55 return r[a]==r[b] && r[a+l]==r[b+l];
56 }
57
58 void da(int *r, int *sa, int n, int m) {
59 int i, j, *x=wa, *y=wb, *t, p;
60
61 for (i=0; i<m; ++i) wc[i] = 0;
62 for (i=0; i<n; ++i) wc[x[i]=r[i]]++;
63 for (i=1; i<m; ++i) wc[i] += wc[i-1];
64 for (i=n-1; i>=0; --i) sa[--wc[x[i]]] = i;
65 for (j=1,p=1; p<n; j*=2,m=p) {
66 for (p=0,i=n-j; i<n; ++i) y[p++] = i;
67 for (i=0; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i]-j;
68 for (i=0; i<n; ++i) wv[i] = x[y[i]];
69 for (i=0; i<m; ++i) wc[i] = 0;
70 for (i=0; i<n; ++i) wc[wv[i]]++;
71 for (i=1; i<m; ++i) wc[i] += wc[i-1];
72 for (i=n-1; i>=0; --i) sa[--wc[wv[i]]] = y[i];
73 for (t=x,x=y,y=t, x[sa[0]]=0, p=1, i=1; i<n; ++i)
74 x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1:p++;
75 }
76 }
77
78 void calheight(int *r, int *sa, int n) {
79 int i, j, k = 0;
80
81 for (i=1; i<=n; ++i) rank[sa[i]] = i;
82 for (i=0; i<n; height[rank[i++]]=k)
83 for (k?k--:0, j=sa[rank[i]-1]; r[j+k]==r[i+k]; ++k) ;
84 }
85
86 bool check(int b, int e) {
87 int cnt = 0;
88
89 memset(visit, false, sizeof(visit));
90 rep(i, b, e+1) {
91 if (!visit[id[sa[i]]]) {
92 visit[id[sa[i]]] = true;
93 ++cnt;
94 }
95 }
96
97 return cnt > ns_;
98 }
99
100 bool judge(int bound, int n) {
101 bool ret = false;
102 int b, e;
103
104 b = e = 0;
105 rep(i, 1, n+1) {
106 if (height[i] >= bound) {
107 e = i;
108 } else {
109 if (check(b, e)) {
110 if (!ret)
111 pn = 0;
112 ret = true;
113 pos[pn++] = sa[b];
114 }
115 b = e = i;
116 }
117 }
118 if (check(b, e)) {
119 if (!ret)
120 pn = 0;
121 ret = true;
122 pos[pn++] = sa[b];
123 }
124
125 return ret;
126 }
127
128 void printSa(int n) {
129 for (int i=1; i<=n; ++i)
130 printf("%d ", sa[i]);
131 putchar(‘\n‘);
132 }
133
134 void printHeight(int n) {
135 for (int i=1; i<=n; ++i)
136 printf("%d ", height[i]);
137 putchar(‘\n‘);
138 }
139
140 void solve() {
141 int n = 0, ml = 0;
142
143 if (ns == 1) {
144 puts(s[0]);
145 return ;
146 }
147
148 rep(i, 0, ns) {
149 for (int j=0; ; ++j) {
150 if (s[i][j] == ‘\0‘) {
151 ml = max(ml, j);
152 break;
153 }
154 id[n] = i;
155 a[n] = s[i][j] - ‘a‘ + 100;
156 ++n;
157 }
158 id[n] = a[n] = i;
159 ++n;
160 }
161
162 --n;
163 da(a, sa, n+1, 130);
164 calheight(a, sa, n);
165
166 #ifndef ONLINE_JUDGE
167 // printSa(n);
168 // printHeight(n);
169 // printf("ml = %d\n", ml);
170 #endif
171
172 int l = 1, r = ml, mid;
173 int ans = 0;
174 ns_ = ns >> 1;
175
176 while (l <= r) {
177 mid = (l + r) >> 1;
178 if (judge(mid, n)) {
179 ans = mid;
180 l = mid + 1;
181 } else {
182 r = mid - 1;
183 }
184 }
185
186 if (ans == 0) {
187 puts("?");
188 return ;
189 }
190
191 char ch;
192
193 rep(i, 0, pn) {
194 rep(j, 0, ans) {
195 ch = a[pos[i]+j] - 100 + ‘a‘;
196 putchar(ch);
197 }
198 putchar(‘\n‘);
199 }
200 }
201
202 int main() {
203 ios::sync_with_stdio(false);
204 #ifndef ONLINE_JUDGE
205 freopen("data.in", "r", stdin);
206 freopen("data.out", "w", stdout);
207 #endif
208
209 int t = 0;
210
211 while (scanf("%d", &ns)!=EOF && ns) {
212 rep(i, 0, ns)
213 scanf("%s", s[i]);
214 if (t++)
215 putchar(‘\n‘);
216 solve();
217 }
218
219 #ifndef ONLINE_JUDGE
220 printf("time = %d.\n", (int)clock());
221 #endif
222
223 return 0;
224 }
数据生成器。
1 from random import randint, shuffle
2 import shutil
3 import string
4
5
6 def GenDataIn():
7 with open("data.in", "w") as fout:
8 t = 20
9 bound = 10**3
10 lc = list(string.lowercase)
11 for tt in xrange(t):
12 n = randint(1, 10)
13 fout.write("%d\n" % (n))
14 for i in xrange(n):
15 length = randint(20, 50)
16 line = ""
17 for j in xrange(length):
18 idx = randint(0, 25)
19 line += lc[idx]
20 fout.write("%s\n" % (line))
21 fout.write("0\n")
22
23
24 def MovDataIn():
25 desFileName = "F:\eclipse_prj\workspace\hdoj\data.in"
26 shutil.copyfile("data.in", desFileName)
27
28
29 if __name__ == "__main__":
30 GenDataIn()
31 MovDataIn()
时间： 2024-11-03 03:44:35