CSES - Aalto Competitive Programming 2024 - wk9 - Wed - Results
Submission details
Task:Longest palindrome
Sender:aalto2024j_003
Submission time:2024-11-06 16:36:38 +0200
Language:C++ (C++17)
Status:READY
Result:ACCEPTED
Test results
testverdicttime
#1ACCEPTED0.00 sdetails
#2ACCEPTED0.00 sdetails
#3ACCEPTED0.03 sdetails
#4ACCEPTED0.03 sdetails
#5ACCEPTED0.04 sdetails
#6ACCEPTED0.04 sdetails
#7ACCEPTED0.05 sdetails
#8ACCEPTED0.03 sdetails
#9ACCEPTED0.00 sdetails
#10ACCEPTED0.00 sdetails
#11ACCEPTED0.01 sdetails
#12ACCEPTED0.00 sdetails
#13ACCEPTED0.00 sdetails
#14ACCEPTED0.00 sdetails
#15ACCEPTED0.00 sdetails
#16ACCEPTED0.02 sdetails

Compiler report

input/code.cpp: In function 'void solve()':
input/code.cpp:60:20: warning: statement has no effect [-Wunused-value]
   60 | #define debug(...) 42
      |                    ^~
input/code.cpp:95:5: note: in expansion of macro 'debug'
   95 |     debug(p);
      |     ^~~~~
input/code.cpp:60:20: warning: statement has no effect [-Wunused-value]
   60 | #define debug(...) 42
      |                    ^~
input/code.cpp:106:5: note: in expansion of macro 'debug'
  106 |     debug(ans, pos);
      |     ^~~~~

Code

#pragma GCC optimize("O3","unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
string to_string(string s) {
return '"' + s + '"';
}
string to_string(const char* s) {
return to_string((string) s);
}
string to_string(bool b) {
return (b ? "true" : "false");
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
bool first = true;
string res = "{";
for (const auto &x : v) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(x);
}
res += "}";
return res;
}
void debug_out() {
cerr << endl;
}
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << to_string(H);
debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
/**
* Author: User adamant on CodeForces
* Source: http://codeforces.com/blog/entry/12143
* Description: For each position in a string, computes p[0][i] = half length of
* longest even palindrome around pos i, p[1][i] = longest odd (half rounded down).
* Time: O(N)
* Status: Stress-tested
*/
array<vi, 2> manacher(const string& s) {
int n = sz(s);
array<vi,2> p = {vi(n+1), vi(n)};
rep(z,0,2) for (int i=0,l=0,r=0; i < n; i++) {
int t = r-i+!z;
if (i<r) p[z][i] = min(t, p[z][l+t]);
int L = i-p[z][i], R = i+p[z][i]-!z;
while (L>=1 && R+1<n && s[L-1] == s[R+1])
p[z][i]++, L--, R++;
if (R>r) l=L, r=R;
}
return p;
}
string s;
int n;
void solve() {
cin >> s;
n = sz(s);
int ans = 0, pos = 0;
auto p = manacher(s);
debug(p);
for (int i = 0; i < n; i++) {
if (p[0][i] * 2 > ans) {
ans = p[0][i] * 2;
pos = i;
}
if (p[1][i] * 2 + 1 > ans) {
ans = p[1][i] * 2 + 1;
pos = i;
}
}
debug(ans, pos);
if (ans & 1) {
int half = ans / 2;
cout << s.substr(pos - half, ans);
} else {
int half = ans / 2;
cout << s.substr(pos - half, ans);
}
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit); // RTE if input wrong datatype
solve();
}

Test details

Test 1

Verdict: ACCEPTED

input
aaaaaaaaaa

correct output
aaaaaaaaaa

user output
aaaaaaaaaa

Test 2

Verdict: ACCEPTED

input
ababababab

correct output
ababababa

user output
ababababa

Test 3

Verdict: ACCEPTED

input
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...

correct output
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...

user output
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...
Truncated

Test 4

Verdict: ACCEPTED

input
ababababababababababababababab...

correct output
ababababababababababababababab...

user output
ababababababababababababababab...
Truncated

Test 5

Verdict: ACCEPTED

input
aztdvxzjwxtrludymvpradgbdpgnrq...

correct output
aztdvxzjwxtrludymvpradgbdpgnrq...

user output
aztdvxzjwxtrludymvpradgbdpgnrq...
Truncated

Test 6

Verdict: ACCEPTED

input
vvfigwwsyxbukedgcfyibvtbclybud...

correct output
vvfigwwsyxbukedgcfyibvtbclybud...

user output
vvfigwwsyxbukedgcfyibvtbclybud...
Truncated

Test 7

Verdict: ACCEPTED

input
abaabaaaaaaabaababbbbbbabaaabb...

correct output
babbbabbbaabbbbaabbbbbbbbaabbb...

user output
babbbabbbaabbbbaabbbbbbbbaabbb...

Test 8

Verdict: ACCEPTED

input
txolestmgyepwrpofxyesjtsfkhjac...

correct output
yxnbaabnxy

user output
yxnbaabnxy

Test 9

Verdict: ACCEPTED

input
ihpohpzoffel

correct output
ff

user output
ff

Test 10

Verdict: ACCEPTED

input
flexflexvpqxierullgcfckjqflexf...

correct output
cfc

user output
cfc

Test 11

Verdict: ACCEPTED

input
aabbabaabbaababbabaababbaabbab...

correct output
abaababbaabbabaababbabaabbaaba...

user output
abaababbaabbabaababbabaabbaaba...
Truncated

Test 12

Verdict: ACCEPTED

input
obsession

correct output
ses

user output
ses

Test 13

Verdict: ACCEPTED

input
abcxcbaxcba

correct output
abcxcba

user output
abcxcba

Test 14

Verdict: ACCEPTED

input
zzabc

correct output
zz

user output
zz

Test 15

Verdict: ACCEPTED

input
aaccaabbaaccaaccaabbaaccaa

correct output
aaccaabbaaccaaccaabbaaccaa

user output
aaccaabbaaccaaccaabbaaccaa

Test 16

Verdict: ACCEPTED

input
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...

correct output
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...

user output
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...
Truncated