Submission #240709

#TimeUsernameProblemLanguageResultExecution timeMemory
240709rqiPalindromes (APIO14_palindrome)C++14
73 / 100
174 ms131076 KiB
#include <bits/stdc++.h> using namespace std; typedef long long ll; typedef long double ld; typedef double db; typedef string str; typedef pair<int,int> pi; typedef pair<ll,ll> pl; typedef pair<db,db> pd; typedef vector<int> vi; typedef vector<ll> vl; typedef vector<db> vd; typedef vector<str> vs; typedef vector<pi> vpi; typedef vector<pl> vpl; typedef vector<pd> vpd; #define mp make_pair #define f first #define s second #define sz(x) (int)x.size() #define all(x) begin(x), end(x) #define rall(x) (x).rbegin(), (x).rend() #define rsz resize #define ins insert #define ft front() #define bk back() #define pf push_front #define pb push_back #define eb emplace_back #define lb lower_bound #define ub upper_bound #define FOR(i,a,b) for (int i = (a); i < (b); ++i) #define F0R(i,a) FOR(i,0,a) #define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i) #define R0F(i,a) ROF(i,0,a) #define trav(a,x) for (auto& a: x) const int MOD = 1e9+7; // 998244353; const int MX = 2e5+5; const ll INF = 1e18; const ld PI = acos((ld)-1); const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; } template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; } int pct(int x) { return __builtin_popcount(x); } int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) int cdiv(int a, int b) { return a/b+!(a<0||a%b == 0); } // division of a by b rounded up, assumes b > 0 int fstTrue(function<bool(int)> f, int lo, int hi) { hi ++; assert(lo <= hi); // assuming f is increasing while (lo < hi) { // find first index such that f is true int mid = (lo+hi)/2; f(mid) ? hi = mid : lo = mid+1; } return lo; } // INPUT template<class A> void re(complex<A>& c); template<class A, class B> void re(pair<A,B>& p); template<class A> void re(vector<A>& v); template<class A, size_t SZ> void re(array<A,SZ>& a); template<class T> void re(T& x) { cin >> x; } void re(db& d) { str t; re(t); d = stod(t); } void re(ld& d) { str t; re(t); d = stold(t); } template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); } template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; } template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); } template<class A> void re(vector<A>& x) { trav(a,x) re(a); } template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); } // TO_STRING #define ts to_string str ts(char c) { return str(1,c); } str ts(bool b) { return b ? "true" : "false"; } str ts(const char* s) { return (str)s; } str ts(str s) { return s; } template<class A> str ts(complex<A> c) { stringstream ss; ss << c; return ss.str(); } str ts(vector<bool> v) { str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]); res += "}"; return res; } template<size_t SZ> str ts(bitset<SZ> b) { str res = ""; F0R(i,SZ) res += char('0'+b[i]); return res; } template<class A, class B> str ts(pair<A,B> p); template<class T> str ts(T v) { // containers with begin(), end() bool fst = 1; str res = "{"; for (const auto& x: v) { if (!fst) res += ", "; fst = 0; res += ts(x); } res += "}"; return res; } template<class A, class B> str ts(pair<A,B> p) { return "("+ts(p.f)+", "+ts(p.s)+")"; } // OUTPUT template<class A> void pr(A x) { cout << ts(x); } template<class H, class... T> void pr(const H& h, const T&... t) { pr(h); pr(t...); } void ps() { pr("\n"); } // print w/ spaces template<class H, class... T> void ps(const H& h, const T&... t) { pr(h); if (sizeof...(t)) pr(" "); ps(t...); } // DEBUG void DBG() { cerr << "]" << endl; } template<class H, class... T> void DBG(H h, T... t) { cerr << ts(h); if (sizeof...(t)) cerr << ", "; DBG(t...); } #ifdef LOCAL // compile with -DLOCAL #define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__) #else #define dbg(...) 0 #endif // FILE I/O void setIn(string s) { freopen(s.c_str(),"r",stdin); } void setOut(string s) { freopen(s.c_str(),"w",stdout); } void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); } void setIO(string s = "") { unsyncIO(); // cin.exceptions(cin.failbit); // throws exception when do smth illegal // ex. try to read letter into int if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO } /** * Description: insert int, query max xor with some int in the trie * Time: O(MXBIT) * Source: CF Algorithms Gym * Verification: January Easy 2018 - Shubham and Subarray Xor */ template<int MX> struct Trie { int nex[MX][27], sz[MX], num = 0; // num is last node in trie int par[MX][30]; Trie() { memset(nex,0,sizeof nex); memset(sz,0,sizeof sz); } int trans(int node, int c){ if(nex[node][c] == 0){ nex[node][c] = ++num; par[num][0] = node; for(int i = 1; i < 30; i++){ par[num][i] = par[par[num][i-1]][i-1]; } } return nex[node][c]; } int getpar(int node, int red){ for(int i = 30-1; i >= 0; i--){ if((1<<i) <= red){ red-=(1<<i); node = par[node][i]; } } return node; } ll traverse(int node = 0, int depth = -1){ //mode 1 --> odd, mode 2 --> even ll curans = 0; for(int i = 0; i < 27; i++){ if(nex[node][i] == 0) continue; ckmax(curans, traverse(nex[node][i], depth+1)); sz[node]+=sz[nex[node][i]]; } ckmax(curans, ll(sz[node])*depth); //dbg(node, sz[node], depth); return curans; } }; Trie<600105> t; /** * Source: http://codeforces.com/blog/entry/12143 * Time: O(N) * Description: length of largest palindrome centered at each character of string * and between every consecutive pair * Verification: http://www.spoj.com/problems/MSUBSTR/ */ ll manacher(str s) { str s1; s1+=char('a'+26); trav(c,s) s1 += c, s1 += char('a'+26); vpi ans(sz(s1)); //length, node in trie int lo = -1, hi = -1; for(int i = 0; i < sz(s1); i++){ int len = 0; int node = t.trans(0, s1[i]-'a'); if(hi < i){ //dbg(i, "1"); } else{ if(ans[hi+lo-i].f <= hi-i){ // dbg(i, "2"); // dbg(lo, hi, hi+lo-i, ans[hi+lo-i]); len = ans[hi+lo-i].f; node = ans[hi+lo-i].s; } else{ //dbg(i, "3"); len = hi-i; node = t.getpar(ans[hi+lo-i].s, ans[hi+lo-i].f-(hi-i)); } } //dbg(len, node); while(i-len-1 >= 0 && i+len+1 < sz(s1)){ if(s1[i-len-1] == s1[i+len+1]){ len++; //dbg(node); node = t.trans(node, s1[i+len]-'a'); } else break; } ans[i] = mp(len, node); t.sz[node]++; if(i+ans[i].f > hi) lo = i-ans[i].f, hi = i+ans[i].f; //dbg(i, ans[i], lo, hi); } //dbg(ans); return t.traverse(); } /// Usage: ps(manacher("abacaba")) int main() { setIO(); string s; cin>> s; ps(manacher(s)); // you should actually read the stuff at the bottom } /* stuff you should look for * int overflow, array bounds * special cases (n=1?) * do smth instead of nothing and stay organized * WRITE STUFF DOWN */

Compilation message (stderr)

palindrome.cpp: In function 'void setIn(std::__cxx11::string)':
palindrome.cpp:128:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setIn(string s) { freopen(s.c_str(),"r",stdin); }
                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
palindrome.cpp: In function 'void setOut(std::__cxx11::string)':
palindrome.cpp:129:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setOut(string s) { freopen(s.c_str(),"w",stdout); }
                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
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