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Submission #633458

# Submission time Handle Problem Language Result Execution time Memory
633458 2022-08-22T13:53:26 Z Lawliet Radio Towers (IOI22_towers) C++17
0 / 100
 1058 ms 28188 KB 
#include "towers.h"
#include <bits/stdc++.h>

using namespace std;

const int maxl = 20;
const int maxn = 100010;
const int inf = 1000000010;

class SparseTable
{
    public:

        void build(int n, vector<int> v, bool mn = false)
        {
            isMin = mn;

            for(int i = 1 ; i <= n ; i++)
                tab[0][i] = (mn ? -v[i] : v[i]);

            for(int k = 1 ; k < maxl ; k++)
                for(int i = 1 ; i + (1 << k) - 1 <= n ; i++)
                    tab[k][i] = max( tab[k - 1][i] , tab[k - 1][i + (1 << (k - 1))] ); 
        }

        int query(int l, int r)
        {
            if( l > r )
                return (isMin ? inf : -inf);

            int t = 31 - __builtin_clz(r - l + 1);
            int ans = max( tab[t][l] , tab[t][r - (1 << t) + 1] );

            return (isMin ? -ans : ans);
        }

    protected:

        bool isMin;
        int tab[maxl][maxn];
};

int n;

int v[maxn];

bool hasBuilt = false;

SparseTable stV, stR, stL, corner;

vector<int> valleys, optL, optR, cL, cR;

bool isValid(int i, int j, int D)
{
    int peak = stV.query( i + 1 , j - 1 );

    if( v[i] <= peak - D && v[j] <= peak - D )
        return true;

    return false;
}

int findOptL(int i, int D)
{
    int l = 1, r = i - 1;

    if( v[i] > stV.query( l , i - 1 ) - D )
        return 0;

    while( l < r )
    {
        int m = ( l + r )/2;
        if( l == r - 1 ) m = r;

        if( v[i] <= stV.query( m , i - 1 ) - D )
            l = m;
        else
            r = m - 1;
    }

    return l;
}

int findOptR(int i, int D)
{
    int l = i + 1, r = n;

    if( v[i] > stV.query( i + 1 , r ) - D )
        return n + 1;

    while( l < r )
    {
        int m = ( l + r )/2;

        if( v[i] <= stV.query( i + 1 , m ) - D )
            r = m;
        else
            l = m + 1;
    }

    return r;
}

void buildHistogram(int D)
{
    optL.resize( n + 1 );
    optR.resize( n + 1 );

    for(int i = 1 ; i <= n ; i++)
    {
        optL[i] = findOptL(i, D);
        optR[i] = findOptR(i, D);
    }
}

void build(int D)
{
    buildHistogram(D);

    stR.build( n , optR , true );
    stL.build( n , optL );

    // Corner Case

    cL.resize( n + 1 , 0 );
    cR.resize( n + 1 , n + 1 );

    for(int i = 1 ; i <= n ; i++)
    {
        cL[ optR[i] ] = min( cL[ optR[i] ] , i );
        cR[ optL[i] ] = min( cR[ optL[i] ] , i );
    }

    vector<int> tmp(n + 1, n + 1);

    for(int i = 1 ; i <= n ; i++)
        tmp[ cL[i] ] = min( tmp[ cL[i] ] , cR[i] );

    corner.build( n , tmp );

    // 

    for(int i = 1 ; i <= n ; i++)
    {
        while( !valleys.empty() )
        {
            int j = valleys.back();

            if( isValid( j , i , D ) )
            {
                valleys.push_back( i );
                break;
            }

            if( v[j] < v[i] )
                break;

            valleys.pop_back();
        }

        if( valleys.empty() )
            valleys.push_back( i );
    }

    hasBuilt = true;
}

void init(int N, vector<int> H) {
    n = N;

    H.insert( H.begin() , 0 );

    for(int i = 1 ; i <= n ; i++)
        v[i] = H[i];

    stV.build( n , H );
}

bool newPairL(int L, int opt)
{
    int l = L, r = optL[opt] - 1;

    if( stR.query( l , r ) < opt )
        return true;

    return false;
}

bool newPairR(int R, int opt)
{
    int l = optR[opt] + 1, r = R;

    if( opt < stL.query( l , r ) )
        return true;

    return false;
}

int max_towers(int L, int R, int D) 
{
    if( !hasBuilt )
        build( D );

    L++; R++;

    if( R - L + 1 <= 2 )
        return 1;

    int pL = lower_bound( valleys.begin() , valleys.end() , L ) - valleys.begin();
    int pR = upper_bound( valleys.begin() , valleys.end() , R ) - valleys.begin();

    if( pL == pR )
    {
        if( corner.query( L , R ) <= R )
            return 2;

        return 1;
    }

    int ans = pR - pL;

    if( newPairL( L , valleys[pL] ) )
        ans++;

    if( newPairR( R , valleys[pR - 1] ) )
        ans++;

    return ans;
}

Subtask #1
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 436 ms 16240 KB 12th lines differ - on the 1st token, expected: '2', found: '1'
2 Halted 0 ms 0 KB -

Subtask #2
0 / 11.0

# Verdict Execution time Memory Grader output
1 Runtime error 2 ms 848 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #3
0 / 12.0

# Verdict Execution time Memory Grader output
1 Runtime error 2 ms 848 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #4
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 612 ms 27976 KB Output is correct
2 Correct 1058 ms 28084 KB Output is correct
3 Correct 830 ms 28120 KB Output is correct
4 Correct 832 ms 28188 KB Output is correct
5 Correct 784 ms 28096 KB Output is correct
6 Correct 889 ms 28184 KB Output is correct
7 Correct 832 ms 28176 KB Output is correct
8 Correct 887 ms 28064 KB Output is correct
9 Correct 701 ms 28016 KB Output is correct
10 Correct 791 ms 28092 KB Output is correct
11 Correct 895 ms 28076 KB Output is correct
12 Incorrect 846 ms 28092 KB 170th lines differ - on the 1st token, expected: '2', found: '1'
13 Halted 0 ms 0 KB -

Subtask #5
0 / 17.0

# Verdict Execution time Memory Grader output
1 Runtime error 243 ms 12812 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #6
0 / 19.0

# Verdict Execution time Memory Grader output
1 Runtime error 2 ms 848 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #7
0 / 23.0

# Verdict Execution time Memory Grader output
1 Incorrect 436 ms 16240 KB 12th lines differ - on the 1st token, expected: '2', found: '1'
2 Halted 0 ms 0 KB -