【HDOJ】4426 Palindromic Substring

综合性很强的一道题目，结合manacher，后缀数组，哈希，RMQ，二分可解。
基本思路是通过manacher可以找到所有可能的回文串，哈希去重，后缀数组二分找数目。最后暴力求解。
需要注意kth需要为__int64。

 /* 4426 */
 #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 __int64 mod = 777777777LL;
 const int seed = ;
 const int INF = 0x3f3f3f3f;
 const int maxn = 1e5+;
 // input
 char s[maxn];
 int val[];
 __int64 V[maxn];
 // manacher
 char ss[maxn*];
 int P[maxn*];
 // sa
 int a[maxn];
 int height[maxn], sa[maxn], rrank[maxn];
 int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
 // RMQ
 int dp[maxn][];
 // Hash
 unsigned __int64 H[maxn];
 // init
 unsigned __int64 Base[maxn], Power[maxn];
 vpii pal;
 set<unsigned __int64> st;

 void init() {
     Base[] = Power[] = ;
     rep(i, , maxn) {
         Base[i] = 1LL * Base[i-] *  % mod;
         Power[i] = 1LL * Power[i-] * seed;
     }
 }

 void init_Hash(int n) {
     H[] = s[] - 'a' + ;
     rep(i, , n)
         H[i] = H[i-] * seed + s[i]-'a'+;
 }

 unsigned __int64 getHash(int l, int r) {
     if (l == )
         return H[r];
     return H[r] - H[l-] * Power[r-l+];
 }

 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,p=,x[sa[]]=, 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) 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);

     ++l;
     int k = ;

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

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

 void Manacher(char *s, int *P, int n) {
     pal.clr();
     st.clr();

     int i, j, mx = , id = ;

     for (i=; i<n; ++i) {
         P[i] = mx>i ? min(P[*id-i], mx-i) : ;
         while (s[i+P[i]] == s[i-P[i]])
             ++P[i];
         if (i+P[i] > mx) {
             for (j=mx; j<i+P[i]; ++j) {
                 int l = *i-j, r = j;
                 l >>= ;
                 r = (r & ) ? (r>>) : (r>>)-;
                 if (l > r)
                     continue;

                 unsigned __int64 hval = getHash(l, r);
                 if (st.find(hval) == st.end()) {
                     st.insert(hval);
                     pal.pb(mp(l, r));
                 }
             }
             mx = i + P[i];
             id = i;
         }
     }
 }

 int getCnt(int fr, int to, int n) {
     int len = to - fr + ;
     int rankfr = rrank[fr];
     int l, r, mid, tmp;
     int L = rankfr, R = rankfr;

     // find left most
     l = , r = rankfr - ;
     while (l <= r) {
         mid = (l + r) >> ;
         tmp = RMQ(mid, rankfr);
         if (tmp >= len) {
             L = mid;
             r = mid - ;
         } else {
             l = mid + ;
         }
     }

     // find right most
     l = rankfr + , r = n;
     while (l <= r) {
         mid = (l + r) >> ;
         tmp = RMQ(rankfr, mid);
         if (tmp >= len) {
             R = mid;
             l = mid + ;
         } else {
             r = mid - ;
         }
     }

     return R - L + ;
 }

 void init_Val(int n) {
     V[] = val[s[]-'a'];
     rep(i, , n)
         V[i] = (V[i-] *  + val[s[i]-'a']) % mod;
 }

 __int64 getVal(int l, int r) {
     if (l == )
         return V[r];
     return (V[r] - V[l-] * Base[r-l+]%mod + mod) % mod;
 }

 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');
 }

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

     int t;
     int n, q;
     __int64 kth;
     int ans;
     vpii vc;

     init();
     scanf("%d", &t);
     while (t--) {
         scanf("%d %d", &n, &q);
         scanf("%s", s);

         // init sa
         rep(i, , n)
             a[i] = s[i]-'a'+;
         a[n] = ;
         da(a, sa, n+, );
         calheight(a, sa, n);
         init_RMQ(n);

         // init Hash
         init_Hash(n);

         // init Manacher
         int l = ;
         ss[l++] = '@';
         // ss[l++] = '#';
         rep(i, , n) {
             ss[l++] = s[i];
             ss[l++] = '#';
         }
         ss[l] = '\0';
         Manacher(ss, P, l);

         // find count of palindromic
         int sz = SZ(pal);
         rep(i, , sz) {
             wc[i] = getCnt(pal[i].fir, pal[i].sec, n);
             pal[i].sec = (pal[i].fir + pal[i].sec) >> ;
         }

         while (q--) {
             scanf("%I64d", &kth);
             rep(i, , )
                 scanf("%d", &val[i]);
             init_Val(n);
             vc.clr();
             rep(i, , sz) {
                 int tmp = getVal(pal[i].fir, pal[i].sec);
                 vc.pb(mp(tmp, wc[i]));
             }
             sort(all(vc));
             ans = -;
             rep(i, , sz) {
                 if (kth <= vc[i].sec) {
                     ans = vc[i].fir;
                     break;
                 } else {
                     kth -= vc[i].sec;
                 }
             }
             printf("%d\n", ans);
         }
         putchar('\n');
     }

     #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**3
         lc = list(string.lowercase)
         uc = list(string.uppercase)
         fout.write("%d\n" % (t))
         for tt in xrange(t):
             n = randint(10**4, 10**5)
             q = randint(30, 40)
             fout.write("%d %d\n" % (n, q))
             line = ""
             for j in xrange(n):
                 idx = randint(0, 25)
                 line += lc[idx]
             fout.write("%s\n" % (line))
             for i in xrange(q):
                 kth = randint(1, 1005)
                 dataList = [kth]
                 for j in xrange(26):
                     val = randint(0, 25)
                     dataList.append(val)
                 fout.write(" ".join(map(str, dataList)) + "\n")

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

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