Submission #142747

#	Time	Username	Problem	Language	Result	Execution time	Memory
142747		liwi	Mousetrap (CEOI17_mousetrap)	C++11	0 / 100	434 ms	76268 KiB

mousetrap

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;

#define scan(x) do{while((x=getchar())<'0'); for(x-='0'; '0'<=(_=getchar()); x=(x<<3)+(x<<1)+_-'0');}while(0)
char _;
#define complete_unique(a) a.erase(unique(a.begin(),a.end()),a.end())
#define all(a) a.begin(),a.end()
#define println printf("\n");
#define readln(x) getline(cin,x);
#define pb push_back
#define endl "\n"
#define INT_INF 0x3f3f3f3f
#define LL_INF 0x3f3f3f3f3f3f3f3f
#define MOD 1000000007
#define mp make_pair
#define fastio cin.tie(0); cin.sync_with_stdio(0);

#define MAXN 1000005

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef unordered_map<int,int> umii;
typedef pair<int,int> pii;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef pair<int,pii> triple;
typedef int8_t byte;

mt19937 g1(time(0));

int randint(int a, int b){return uniform_int_distribution<int>(a, b)(g1);}
ll randlong(ll a,ll b){return uniform_int_distribution<long long>(a, b)(g1);}

ll gcd(ll a, ll b){return b == 0 ? a : gcd(b, a % b);}
ll lcm(ll a, ll b){return a*b/gcd(a,b);}
ll fpow(ll  b, ll exp, ll mod){if(exp == 0) return 1;ll t = fpow(b,exp/2,mod);if(exp&1) return t*t%mod*b%mod;return t*t%mod;}
ll divmod(ll i, ll j, ll mod){i%=mod,j%=mod;return i*fpow(j,mod-2,mod)%mod;}

int num_nodes,T,M;
ll dp[MAXN],res;
bool marked[MAXN];
vector<int> connections[MAXN];

void mark(int node, int prev){
	if(node == T){
		marked[node] = true;
		return;
	}
	for(int check:connections[node]){
		if(check == prev) continue;
		mark(check,node);
		if(marked[check]){
			marked[node] = true;
			break;
		}
	}
}

ll calc(int node, int prev){
	ll gd = -1;
	for(int check:connections[node]){
		if(marked[check] || check == prev) continue;
		gd = max(gd,calc(check,node));
	}
	return dp[node] = gd+1;
}

void solve(int node, int prev){
	if(node == T) return;
	res+=calc(node,prev);
	for(int check:connections[node]){
		if(check == prev || !marked[check]) continue;
		solve(check,node);
	}
}

int main(){
	scanf("%d %d %d",&num_nodes,&T,&M);
	for(int i=1; i<num_nodes; i++){
		int a,b; scanf(" %d %d",&a,&b);
		connections[a].pb(b);
		connections[b].pb(a);
	}
	mark(M,-1);
	solve(M,-1);
	printf("%lld\n",res);
}

Compilation message (stderr)

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:84:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d",&num_nodes,&T,&M);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:86:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int a,b; scanf(" %d %d",&a,&b);
            ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35