2018南京ICPCMediocre String Problem 马拉车

hash+二分求出最长公共前缀

然后马拉车+前缀和计数

 #include <cstdio>
 #include <cstring>
 #include <queue>
 #include <cmath>
 #include <algorithm>
 #include <set>
 #include <iostream>
 #include <map>
 #include <stack>
 #include <string>
 #include <vector>
 #define  pi acos(-1.0)
 #define  eps 1e-9
 #define  fi first
 #define  se second
 #define  rtl   rt<<1
 #define  rtr   rt<<1|1
 #define  bug         printf("******\n")
 #define  mem(a,b)    memset(a,b,sizeof(a))
 #define  name2str(x) #x
 #define  fuck(x)     cout<<#x" = "<<x<<endl
 #define  f(a)        a*a
 #define  sf(n)       scanf("%d", &n)
 #define  sff(a,b)    scanf("%d %d", &a, &b)
 #define  sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)
 #define  sffff(a,b,c,d) scanf("%d %d %d %d", &a, &b, &c, &d)
 #define  pf          printf
 #define  FRE(i,a,b)  for(i = a; i <= b; i++)
 #define  FREE(i,a,b) for(i = a; i >= b; i--)
 #define  FRL(i,a,b)  for(i = a; i < b; i++)+
 #define  FRLL(i,a,b) for(i = a; i > b; i--)
 #define  FIN         freopen("data.txt","r",stdin)
 #define  gcd(a,b)    __gcd(a,b)
 #define  lowbit(x)   x&-x
 using namespace std;
 typedef long long  LL;
 typedef unsigned long long ULL;
 const int mod = 1e9 + ;
 const int maxn = 2e5 + ;
 const int INF = 0x3f3f3f3f;
 const LL INFLL = 0x3f3f3f3f3f3f3f3fLL;
 int lens, lent;
 char s[maxn << ], t[maxn], ss[maxn << ];
 int d[maxn], r[maxn << ];

 int Init() {
     int len = strlen ( s +  );
     ss[] = '$';
     ss[] = '#';
     int j = ;
     for ( int i = ; i <= len; i++ ) ss[j++] = s[i], ss[j++] = '#';
     ss[j] = '\0';
     return j;
 }
 void Manacher() {
     int len = Init();
     int p, mx = ;
     for ( int i = ; i < len; i++ ) {
         if ( i < mx ) r[i] = min ( r[ * p - i], mx - i );
         else r[i] = ;
         while ( ss[i - r[i]] == ss[i + r[i]] ) r[i]++;
         if ( mx < i + r[i] ) p = i, mx = i + r[i];
     }
     for ( int i = ; i < len; i++ ) {
         if ( ss[i] == '#' && r[i] ==  ) continue;
         int x = i /  - r[i] /  + , y = i /  + r[i] /  - ! ( i &  );
         d[x]++;
         d[ ( x + y ) /  + ]--;
     }
 }
 ULL p[maxn], h1[maxn], h2[maxn],seed=;

 ULL getkey ( ULL *a, int l, int r ) {
     return ( a[r] - a[l - ] * p[r - l + ] );
 }
 bool check ( int len, int P, int lent ) {
     if ( getkey ( h1, P - len + , P ) == getkey ( h2, lent - len + , lent ) ) return true;
     return false;
 }
 int main() {
     p[] = ;
     for ( int i = ; i < maxn; i++ ) p[i] = p[i - ] * seed  ;
     while ( ~scanf ( "%s%s", s + , t +  ) ) {
         lens = strlen ( s +  );
         lent = strlen ( t +  );
         for ( int i = ; i <= lens; i++ ) d[i] = ;
         Manacher();
         for ( int i = ; i <= lens; i++ ) d[i] += d[i - ];
         reverse ( t+, t + lent+ );
         for ( int i = ; i <= lens; ++i ) h1[i] = ( h1[i-] * seed + s[i] ) ;
         for ( int i = ; i <= lent; ++i ) h2[i] = ( h2[i-] * seed + t[i] ) ;
         LL res = ;
         for ( int i = ; i < lens; ++i ) {
             if ( s[i] != t[lent] ) continue;
             int l = , r = min ( lent, i+ ), mid, ans = ;
             while ( r >= l ) {
                 mid = ( l + r ) >> ;
                 if ( check ( mid, i, lent ) ) ans = mid, l = mid + ;
                 else r = mid - ;
             }
             res += ( LL ) ans * d[i + ];
         }
         printf ( "%lld\n", res );
     }
 }