Submission #1883031

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Source Code Expand

#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cout << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cout<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 200010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 29;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
///////////////////////////////////////////////////////////////////////////////////////////////////

int N;
int S[MAX_N];
int X[MAX_N];
vector<int> G[MAX_N];

bool loop(int v, int p) {
	vector<vi> dp(2, vi(X[v] + 1, inf));
	int now = 0, next = 1;
	dp[0][0] = 0;
	rep(i, 0, sz(G[v])) {
		fill(dp[next].begin(), dp[next].begin() + X[v] + 1, inf);
		int n = G[v][i];
		loop(n, v);
		rep(w, 0, X[v] + 1) {
			if(dp[now][w] == inf) continue;
			if(w + X[n] <= X[v]) MIN(dp[next][w + X[n]], dp[now][w] + S[n]);
			if(w + S[n] <= X[v]) MIN(dp[next][w + S[n]], dp[now][w] + X[n]);
		}
		swap(now, next);
	}
	S[v] = inf;
	rep(i, 0, X[v] + 1) MIN(S[v], dp[now][i]);
	if(S[v] != inf) return true;
	else return false;
}
		

void solve() {
	cin >> N;
	fill(S, S + N, inf);
	rep(i, 0, N - 1) {
		int a; cin >> a; a--;
		G[a].pb(i + 1);
	}
	rep(i, 0, N) cin >> X[i];
	if(loop(0, -1)) cout << "POSSIBLE\n";
	else cout << "IMPOSSIBLE\n";
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
#ifdef LOCAL
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
#ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
	return 0;
}

Submission Info

Judge Result