Submission #790474

#	Time	Username	Problem	Language	Result	Execution time	Memory
790474		Username4132	Mađioničar (COI22_madionicar)	C++14	13 / 100	1571 ms	684 KiB

Main

#include<iostream>
#include<cassert>
using namespace std;
#define forn(i, n) for(int i=0; i<(int)n; ++i)
#define forsn(i, s, n) for(int i=s; i<(int)n; ++i)

const int MAXN=400010;
int n, len[MAXN];

bool isPalindrome(int l, int r){
    if(l==r) return true;
    if(l==0 || r==2*n) return false;
    int ret;
    l = (l+2)/2, r = (r+1)/2;
    if(l==r) return true;
    printf("? %d %d\n", l, r);
    fflush(stdout);
    scanf("%d", &ret);
    return ret;
}

int main(){
    scanf("%d", &n);
    int l=1, r=1, mx=0;
    forsn(i, 1, 2*n){
        assert(l+r-i >= 0);
        len[i]=max(0, min(r-i, len[l+r-i]));
        while(isPalindrome(i-len[i], i+len[i])) ++len[i];
        if(i+len[i] > r) l=i-len[i], r=i+len[i];
    }
    forsn(i, 1, 2*n){
        if(i&1) mx = max(mx, (((len[i]-1)/2)*2) + 1);
        else mx = max(mx, ((len[i]/2)*2));
    }
    printf("! %d\n", mx);
}

Compilation message (stderr)

Main.cpp: In function 'bool isPalindrome(int, int)':
Main.cpp:18:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |     scanf("%d", &ret);
      |     ~~~~~^~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:23:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 0 / 25
• Subtask 3: 0 / 25
• Subtask 4: 0 / 37