【HDOJ】2459 Maximum repetition substring

后缀数组+RMQ。

 /* 2459 */
 #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 INF = 0x3f3f3f3f;
 const int maxn = 1e5+;
 char s[maxn];
 int a[maxn];
 int rrank[maxn], height[maxn], sa[maxn];
 int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
 int dp[maxn][];
 int mx[maxn], L[maxn];

 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=; i<m; ++i) wc[i] = ;
     for (i=; i<n; ++i) wc[x[i]=r[i]]++;
     for (i=; i<m; ++i) wc[i] += wc[i-];
     for (i=n-; i>=; --i) sa[--wc[x[i]]] = i;
     for (j=,p=; p<n; j*=, m=p) {
         for (p=,i=n-j; i<n; ++i) y[p++] = i;
         for (i=; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;
         for (i=; i<n; ++i) wv[i] = x[y[i]];
         for (i=; i<m; ++i) wc[i] = ;
         for (i=; i<n; ++i) wc[x[i]]++;
         for (i=; i<m; ++i) wc[i] += wc[i-];
         for (i=n-; i>=; --i) sa[--wc[wv[i]]] = y[i];
         for (t=x, x=y, y=t, p=, i=, x[sa[]]=; i<n; ++i)
             x[sa[i]] = cmp(y, sa[i-], sa[i], j) ? p- : p++;
     }
 }

 void calheight(int *r, int *sa, int n) {
     int i, j, k = ;

     for (i=; i<=n; ++i) rrank[sa[i]] = i;
     for (i=; i<n; height[rrank[i++]]=k)
     for (k?k--:, j=sa[rrank[i]-]; r[j+k]==r[i+k]; ++k) ;
 }

 void init_RMQ(int n) {
     int i, j;

     for (i=; i<=n; ++i)
         dp[i][] = height[i];
     dp[][] = INF;
     for (j=; (<<j)<=n; ++j)
         for (i=; i+(<<j)-<=n; ++i)
             dp[i][j] = min(dp[i][j-], dp[i+(<<(j-))][j-]);
 }

 int RMQ(int l, int r) {
     if (l > r)
         swap(l, r);

     int k = ;
     ++l;
     while (<<(k+) <= r-l+)
         ++k;

     return min(dp[l][k], dp[r-(<<k)+][k]);
 }

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

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

 void solve() {
     int n;

     for (int i=; ; ++i) {
         if (s[i] == '\0') {
             n = i;
             break;
         }
         a[i] = s[i] - 'a' + ;
     }
     a[n] = ;

     da(a, sa, n+, );
     calheight(a, sa, n);
     init_RMQ(n);

     int n_ = n >> , tmp;
     rep(i, , n_) {
         mx[i] = ;
         for (int p=, q=i; q<n; p=q, q+=i) {
             tmp = RMQ(rrank[p], rrank[q]);
             mx[i] = max(mx[i], tmp/i+);
             if (tmp%i) {
                 tmp = RMQ(rrank[p-(i-tmp%i)], rrank[q-(i-tmp%i)]);
                 mx[i] = max(mx[i], tmp/i+);
             }
         }
     }

     int ans = ;
     rep(i, , n_)
         ans = max(ans, mx[i]);

     int ln = ;
     rep(i, , n_) {
         if (mx[i] == ans) {
             L[ln++] = i;
         }
     }

     int beg = , len = ;

     rep(i, , n+) {
         rep(j, , ln) {
             int p = sa[i];
             if (p+L[j] >= n)
                 continue;

             tmp = RMQ(rrank[p], rrank[p+L[j]]);
             if (tmp/L[j]+ >= ans) {
                 beg = p;
                 len = L[j] * ans;
                 goto _output;
             }
         }
     }

     _output:
     s[beg+len] = '\0';
     puts(s+beg);
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     int t = ;

     while (scanf("%s", s)!=EOF && (s[]!='#')) {
         printf("Case %d: ", ++t);
         solve();
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }

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**2
         lc = list(string.lowercase)
         for tt in xrange(t):
             length = randint(100, 500)
             line = ""
             for i in xrange(length):
                 idx = randint(0, 25)
                 line += lc[idx]
             fout.write("%s\n" % line)
         fout.write("#\n")

 def MovDataIn():
     desFileName = "F:\eclipse_prj\workspace\hdoj\data.in"
     shutil.copyfile("data.in", desFileName)

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