Submission #1311719

#	Time	Username	Problem	Language	Result	Execution time	Memory
1311719		darkdevilvaqif	Fountain (eJOI20_fountain)	C++20	100 / 100	166 ms	22352 KiB

fountain

/*
  _      __        __         __        ____                    ___    _                   __
 | | /| / / ___ _ / /_ ____  / /       / __ \  ___  ___        / _ \  (_) ___  ____ ___   / /
 | |/ |/ / / _ `// __// __/ / _ \     / /_/ / / _ \/ -_)      / ___/ / / / -_)/ __// -_) /_/ 
 |__/|__/  \_,_/ \__/ \__/ /_//_/     \____/ /_//_/\__/      /_/    /_/  \__/ \__/ \__/ (_)  
                                                                                             
*/

#pragma GCC optimize("O3")
#pragma GCC optimize ("unroll-loops")
// #pragma GCC target("avx2")
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define ld long double
#define all(v, l) v.begin() + l, v.end()
#define rall(v, l) v.rbegin(), v.rend() - l
#define pb push_back
#define rsz resize
#define fi first
#define se second
#define LMAX LLONG_MAX
#define LMIN LLONG_MIN
#define IMAX INT_MAX
#define IMIN INT_MIN
#define endl "\n"
#define newline cout << endl;
using namespace std;
 
// constants
const int LOG = 20;

// functions
int GCD(int A, int B);
int LCM(int A, int B);
int power(int base, int exponent);

// structs
struct node
{
    int P, S;  
};

struct graph
{
    vector <vector <node> > up;
    
    void prep(int n)
    {
        up.assign(n + 1, vector <node>(LOG, {0, 0}));   
    }
    
    void build()
    {
        for (int k = 1; k < LOG; k++)
        {
            for (int v = 1; v < (int)up.size(); v++)
            {
                int u = up[v][k - 1].P;
                
                if (!u)
                {
                    up[v][k] = {0, up[v][k - 1].S};
                    continue;
                }
                up[v][k].P = up[u][k - 1].P;
                up[v][k].S = (up[v][k - 1].S == IMAX || up[u][k - 1].S == IMAX ? IMAX : up[v][k - 1].S + up[u][k - 1].S);
            }
        }
    }
    
    int ask(int v, int x, vector <int>&vals)
    {
        if (x <= vals[v])
        {
            return v;
        }
        
        x -= vals[v];
        int u = v;
        for (int k = LOG - 1; k >= 0; k--)
        {
            if (up[u][k].P && up[u][k].S < x)
            {
                x -= up[u][k].S;
                u = up[u][k].P;
            }
        }
        
        return up[u][0].P;
    }
};

// globals

// variables
int n, q;

// iterators
int i;

// notes
/*
One piece on top!

 -stuff you should look for-
* int overflow, array bounds
* special cases (n=1?)
* do something instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH

continue - skip the rest in the loop
*/
 
void solve()
{
    cin >> n >> q;
    array <vector <int>, 2> v;
    v[0].rsz(n + 1), v[1].rsz(n + 1);
    for (i = 1; i <= n; i++)
    {
        cin >> v[0][i] >> v[1][i];
    }
    
    graph G;
    G.prep(n + 1);
    {
        stack <int> st;
        for (i = 1; i <= n; i++)
        {
            while (!st.empty() && v[0][st.top()] < v[0][i])
            {
                G.up[st.top()][0] = {i, v[1][i]};
                st.pop();
            }   
            
            st.push(i);
        }
        
        while (!st.empty())
        {
            G.up[st.top()][0] = {0, IMAX};
            st.pop();
        }
    }
    
    G.build();
    
    while (q--)
    {
        int k, x;
        cin >> k >> x;
        
        cout << G.ask(k, x, v[1]) << endl;
    }
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
        newline
    }
}
 
int GCD(int A, int B)
{
    if (!A)
    {
        return B;
    }
    return GCD(B % A, A);
}

int LCM(int A, int B)
{
    return A * B / GCD(A, B);
}

int power(int base, int exponent)
{
    int res = 1;
    while (exponent) 
    {
        if (exponent & 1)
        { 
            res *= base;
        }
        base *= base;
        exponent >>= 1;    
    }
    return res;
}

/*
$$$$$$$$\ $$$$$$$$\ 
$$  _____|\____$$  |
$$ |          $$  / 
$$$$$\       $$  /  
$$  __|     $$  /   
$$ |       $$  /    
$$$$$$$$\ $$$$$$$$\ 
\________|\________|
*/

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40