Submission #689782

#	Time	Username	Problem	Language	Result	Execution time	Memory
689782		jamezzz	The Xana coup (BOI21_xanadu)	C++17	0 / 100	185 ms	30804 KiB

xanadu

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

#ifdef DEBUG
#define dbg(...) printf(__VA_ARGS__);
#define getchar_unlocked getchar
#else
#define dbg(...)
#endif
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define psf push_front
#define ppb pop_back
#define ppf pop_front
#define sz(x) (int)x.size()
#define mnto(x,y) x=min(x,(__typeof__(x))y)
#define mxto(x,y) x=max(x,(__typeof__(x))y)
#define INF 1023456789
#define LINF 1023456789123456789
#define all(x) x.begin(),x.end()
#define lb(x,v) (lower_bound(all(x),v)-x.begin())
#define ub(x,v) (upper_bound(all(x),v)-x.begin())
#define disc(x) sort(all(x));x.resize(unique(all(x))-x.begin());
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> iii;
typedef tuple<int,int,int,int> iiii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
mt19937 rng(time(0));

#define mod 1000000007

inline int add(int a,int b){
	int r=a+b;
	while(r>=mod)r-=mod;
	while(r<0)r+=mod;
	return r;
}

inline int mult(int a,int b){
	return (int)(((ll)(a*b))%mod);
}

inline int rd(){
	int x=0;
	char ch=getchar_unlocked();
	while(!(ch&16))ch=getchar();//keep reading while current character is whitespace
    while(ch&16){//this will break when ‘\n’ or ‘ ‘ is encountered
		x=(x<<3)+(x<<1)+(ch&15);
		ch=getchar_unlocked();
	}
	return x;
}

#define maxn 100005

int n,a[maxn],dp[maxn][2][2];
vi AL[maxn];

int dfs(int u,int target,int toggle,int par){
	if(dp[u][target][toggle]!=-1)return dp[u][target][toggle];
	int tot=0,add=INF,pari=0;
	for(int v:AL[u]){
		if(v==par)continue;
		int x=dfs(v,1-toggle,0,u),y=dfs(v,1-toggle,1,u);
		tot+=min(x,y);
		pari+=(x==min(x,y))?0:1;
		add=min(add,abs(x-y));
	}
	if((a[u]+pari+toggle)%2==target)tot+=add;
	pf("dfs %d %d %d: %d\n",u,target,toggle,tot+toggle);
	return dp[u][target][toggle]=tot+toggle;
}

int main(){
	sf("%d",&n);
	for(int i=0;i<n-1;++i){
		int x,y;sf("%d%d",&x,&y);
		AL[x].pb(y),AL[y].pb(x);
	}
	for(int i=1;i<=n;++i)sf("%d",&a[i]);
	memset(dp,-1,sizeof dp);
	int ans=min(dfs(1,1,0,-1),dfs(1,1,1,-1));
	if(ans>=INF)pf("impossible\n");
	else pf("%d\n",ans);
}

Compilation message (stderr)

xanadu.cpp: In function 'int main()':
xanadu.cpp:83:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |  sf("%d",&n);
      |    ^
xanadu.cpp:85:13: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |   int x,y;sf("%d%d",&x,&y);
      |             ^
xanadu.cpp:88:25: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |  for(int i=1;i<=n;++i)sf("%d",&a[i]);
      |                         ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 40
• Subtask 5: 0 / 30