Submission #765452

#	Time	Username	Problem	Language	Result	Execution time	Memory
765452		GrindMachine	Hidden Sequence (info1cup18_hidden)	C++17	100 / 100	102 ms	300 KiB

hidden

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

refs:
https://codeforces.com/blog/entry/58101?#comment-420242

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "grader.h"

vector<int> findSequence (int n)
{
    int zeros = 0, ones = 0;
    bool flag = false;

    rep1(i,n/2+1){
        vector<int> v;
        rep1(j,i) v.pb(0);
        if(isSubsequence(v)){
            zeros++;
        }
        else{
            flag = true;
            break;
        }
    }   

    if(flag){
        ones = n-zeros;
    }
    else{
        rep1(i,n/2+1){
            vector<int> v;
            rep1(j,i) v.pb(1);
            if(isSubsequence(v)){
                ones++;
            }
            else{
                flag = true;
                break;
            }
        }

        assert(flag);
        zeros = n-ones;
    }

    vector<int> ans(n);
    int lim = n/2+1;

    rep1(i,ones){
        // find the pos of the ith one
        // a = bef 0, b = bef 1
        // c = aft 0, d = aft 1
        // when fixing the ith one, we already know the values of b and d
        // we know the pos of 1 if we know pair (a,d) or (b,c) (some before + some after)
        // a+b+c+d = n-1
        // (a+d) + (b+c) = n-1
        // min(a+d, b+c) <= (n-1)/2
        // min(a+d+1, b+c+1) <= (n-1)/2 + 1

        int b = i-1;
        int d = ones-i;

        // first try (a,d)
        bool found = false;
        int aa = 0, cc = 0;

        rep1(a,n){
            if(a+d+1 > lim) break;
            vector<int> v;
            rep1(j,a) v.pb(0);
            v.pb(1);
            rep1(j,d) v.pb(1);
            bool ok = isSubsequence(v);

            if(ok){
                aa++;
            }
            else{
                found = true;
                break;
            }
        }

        int pos = -1;

        if(found){
            pos = aa + (ones-d-1);
        }
        else{
            // try (b,c)
            rep1(c,n){
                if(b+c+1 > lim) break;
                vector<int> v;
                rep1(j,b) v.pb(1);
                v.pb(1);
                rep1(j,c) v.pb(0);
                bool ok = isSubsequence(v);

                if(ok){
                    cc++;
                }
                else{
                    found = true;
                    break;
                }
            }

            // assert(found);

            pos = b + (zeros-cc);
        }

        ans[pos] = 1;
    }

    return ans;
}

Compilation message (stderr)

grader.cpp: In function 'int main()':
grader.cpp:28:26: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
   28 |     fprintf (fifo_out, "%d\n", ans.size ());
      |                         ~^     ~~~~~~~~~~~
      |                          |              |
      |                          int            std::vector<int>::size_type {aka long unsigned int}
      |                         %ld
grader.cpp:29:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for (int i=0; i<ans.size () && i < N; i++)
      |                   ~^~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 80 / 80