Submission #704570

#	Time	Username	Problem	Language	Result	Execution time	Memory
704570		thrasherr_1	Fountain (eJOI20_fountain)	C++17	0 / 100	1554 ms	11112 KiB

fountain

#include <bits/stdc++.h>
using namespace std ;

#define ff first
#define ss second
#define ll long long
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define ones(x) __builtin_popcount(x)
#define remove(v)  v.erase(unique(all(v)), v.end())
#define rep(i, a, b) for(int i = a; i <= b; i++)
#define per(i, a, b) for(int i = a; i >= b; i--)

#ifdef local
#include "C:\debug.h"
#else
#define dbg(x...) 42
#endif

#define int ll

const int N = 1e5 + 2 ;

int n , q , d[N] , c[N] , up[N][19] , dp[N][19] , used[N] ;

vector<int> g[N] ;

void dfs(int v , int p) {
    used[v] = 1 ;
    // if(v != p) {
        up[v][0] = p ;
        dp[v][0] = c[v] ;
        if(v != p) dp[v][0] += c[p] ;
        int last = p ;
        rep(i , 1 , 17) {
            up[v][i] = up[up[v][i - 1]][i - 1] ;
            if(up[v][i] == up[v][i - 1]) {
                dp[v][i] = dp[v][i - 1] ;
            }else{
                dp[v][i] = dp[up[v][i - 1]][i - 1] + c[v] ;
            }
        }
    // }n
    for(auto& to : g[v]) {
        if(to != p) {
            dfs(to , v) ;
        }
    }
}

void solve(){
    cin >> n >> q ;
    rep(i , 1 , n) {
        cin >> d[i] >> c[i] ;
    }
    stack<pair<int,int>> s ;
    per(i , n , 1){
        while(sz(s) && s.top().first <= d[i]) s.pop() ;
        if(sz(s)) g[s.top().second].pb(i) ;
        s.push({d[i] , i}) ;
    }
    rep(i , 1 , n) {
        if(!used[i]) {
            int pr = i ;
            dfs(i , pr) ;
        }
    }
    // rep(i , 1 , n) {
        // rep(j , 0 , 17) {
            // cout << dp[i][j] << ' ' ; 
        // }
        // cout << "\n" ;
    // }
    rep(i , 1 , q) {
        int ind , k ; cin >> ind >> k ;
        if(c[ind] >= k) {
            cout << ind << "\n" ;
            continue; 
        }
        if(dp[ind][17] < k) {
            cout << "0\n" ;
        }else{
            per(j , 17 , 0) {
                if(dp[ind][0] >= k) {
                    k -= dp[ind][0] ;
                    ind = up[ind][0] ;
                    break ;
                }else
                if(dp[ind][j] <= k) {
                    k -= dp[ind][j] ;
                    ind = up[ind][j] ;
                    k += c[ind] ;
                    if(k == 0) break ;
                }
            }
            if(k > 0) ind = up[ind][0] ;
            cout << ind << "\n" ;
        }
    }
}

signed main () {
	ios::sync_with_stdio(false) ;
	cin.tie(0) ;
	int test = 1 ;
	// cin >> test ; 
	for(int i = 1 ; i <= test ; i++) {
		solve() ;
	}
}

Compilation message (stderr)

fountain.cpp: In function 'void dfs(long long int, long long int)':
fountain.cpp:37:13: warning: unused variable 'last' [-Wunused-variable]
   37 |         int last = p ;
      |             ^~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40