【POJ】3415 Common Substrings

后缀数组可解。使用单调栈优化。

 /* 3415 */
 #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 = 1e5+;
 const int maxn = maxl * ;
 char as[maxl], bs[maxl];
 int a[maxn];
 int rank[maxn], height[maxn], sa[maxn];
 int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
 int S[maxn][];
 int K;

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

     for (int i=; ; ++i) {
         if (as[i] == '\0') {
             nn = i;
             break;
         }
         a[n++] = as[i];
     }
     a[n++] = ;
     for (int i=; ; ++i) {
         if (bs[i] == '\0') {
             break;
         }
         a[n++] = bs[i];
     }
     a[n] = ;

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

     int top;
     __int64 tot, ans = ;

     // handle as with bs
     top = ;
     tot = ;
     rep(i, , n+) {
         if (height[i] < K) {
             top = ;
             tot = ;
         } else {
             int cnt = ;
             if (sa[i-] < nn) {
                 ++cnt;
                 tot += height[i] - K + ;
             }
             while (top && height[i]<=S[top-][]) {
                 --top;
                 tot -= 1LL * S[top][] * (S[top][] - height[i]);
                 cnt += S[top][];
             }
             S[top][] = height[i];
             S[top][] = cnt;
             ++top;
             if (sa[i] > nn)
                 ans += tot;
         }
     }

     tot = ;
     top = ;
     rep(i, , n+) {
         if (height[i] < K) {
             tot = ;
             top = ;
         } else {
             int cnt = ;
             if (sa[i-] > nn) {
                 ++cnt;
                 tot += height[i] - K + ;
             }
             while (top && height[i]<=S[top-][]) {
                 --top;
                 tot -= 1LL * S[top][] * (S[top][] - height[i]);
                 cnt += S[top][];
             }
             S[top][] = height[i];
             S[top][] = cnt;
             ++top;
             if (sa[i] < nn)
                 ans += tot;
         }
     }

     printf("%I64d\n", ans);
 }

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

     while (scanf("%d", &K)!=EOF && K) {
         scanf("%s%s", as, bs);
         solve();
     }

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

     return ;
 }

数据发生器。

 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):
             k = randint(1, 10)
             fout.write("%d\n" % (k))
             length = randint(100, 500)
             line = ""
             for i in xrange(length):
                 idx = randint(0, 25)
                 line += lc[idx]
             fout.write("%s\n" % line)
             length = randint(100, 500)
             line = ""
             for i in xrange(length):
                 idx = randint(0, 25)
                 line += lc[idx]
             fout.write("%s\n" % line)
         fout.write("0\n")

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

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