Submission #973055

#	Time	Username	Problem	Language	Result	Execution time	Memory
973055		Mher777	The Xana coup (BOI21_xanadu)	C++17	100 / 100	66 ms	33472 KiB

xanadu

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <algorithm>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <utility>
#include <random>
#include <cassert>
#include <fstream>
using namespace std;
mt19937 rnd(7069);

/* -------------------- Typedefs -------------------- */

typedef int itn;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef float fl;
typedef long double ld;

/* -------------------- Usings -------------------- */

using vi = vector<int>;
using vll = vector<ll>;
using mii = map<int, int>;
using mll = map<ll, ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

/* -------------------- Defines -------------------- */

#define ff first
#define ss second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mpr make_pair
#define yes cout<<"Yes\n"
#define no cout<<"No\n"
#define all(x) (x).begin(), (x).end()
#define USACO freopen("feast.in", "r", stdin); freopen("feast.out", "w", stdout);

/* -------------------- Constants -------------------- */

const int dx[8] = { -1, 0, 1, 0, -1, -1, 1, 1 };
const int dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 };
const int MAX = int(1e9 + 5);
const ll MAXL = ll(1e18) + 5ll;
const ll MOD = ll(1000000007);
const ll MOD2 = ll(998244353);

/* -------------------- Functions -------------------- */

void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

void precision(int x) {
    cout.setf(ios::fixed | ios::showpoint);
    cout.precision(x);
}

ll gcd(ll a, ll b) {
    if (a == 0 || b == 0) return(max(a, b));
    while (b) {
        a %= b;
        swap(a, b);
    }
    return a;
}

ll lcm(ll a, ll b) {
    return a / gcd(a, b) * b;
}

ll range_sum(ll a, ll b) {
    if (a > b) return 0ll;
    ll dif = a - 1, cnt = b - a + 1;
    ll ans = ((b - a + 1) * (b - a + 2)) / 2;
    ans += ((b - a + 1) * dif);
    return ans;
}

string dec_to_bin(ll a) {
    string s = "";
    for (ll i = a; i > 0; ) {
        ll k = i % 2;
        i /= 2;
        char c = k + 48;
        s += c;
    }
    if (a == 0) {
        s = "0";
    }
    reverse(all(s));
    return s;
}

ll bin_to_dec(string s) {
    ll num = 0;
    for (int i = 0; i < s.size(); i++) {
        num *= 2ll;
        num += (s[i] - '0');
    }
    return num;
}

ll factorial_by_mod(ll n, ll mod) {
    ll ans = 1;
    ll num;
    for (ll i = 1; i <= n; ++i) {
        num = i % mod;
        ans *= num;
        ans %= mod;
    }
    return ans;
}

int isPrime(ll a) {
    if (a == 1) return 0;
    for (ll i = 2; i * i <= a; i++) {
        if (a % i == 0) return 0;
    }
    return 1;
}

ll binpow(ll a, ll b) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
        }
        b >>= 1;
        a *= a;
    }
    return ans;
}

ll binpow_by_mod(ll a, ll b, ll mod) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
            ans %= mod;
        }
        b >>= 1;
        a *= a;
        a %= mod;
    }
    return ans;
}

/* -------------------- Solution -------------------- */

const int N = 100005, M = 5;
int a[N], dp[N][M][M], check[N][M][M];
vi g[N];
int n;

void dfs(int u = 1, int p = 1) {
    bool f = true;
    for (auto to : g[u]) {
        if (to == p) continue;
        f = false;
        dfs(to, u);
    }
    if (f) {
        if (a[u] == 1) {
            check[u][1][0] = 1;
            dp[u][1][0] = 0;
            check[u][2][1] = 1;
            dp[u][2][1] = 1;
        }
        else {
            check[u][2][0] = 1;
            dp[u][2][0] = 0;
            check[u][1][1] = 1;
            dp[u][1][1] = 1;
        }
        return;
    }
    int mn = MAX;
    int cur = a[u], cnt = 0;
    f = true;
    for (auto to : g[u]) {
        if (to == p) continue;
        if (check[to][2][0] && check[to][2][1]) {
            if (dp[to][2][0] < dp[to][2][1]) {
                cnt += dp[to][2][0];
            }
            else {
                cnt += dp[to][2][1];
                cur ^= 1;
            }
            mn = min(mn, abs(dp[to][2][0] - dp[to][2][1]));
        }
        else if (check[to][2][0]) {
            cnt += dp[to][2][0];
        }
        else if (check[to][2][1]) {
            cnt += dp[to][2][1];
            cur ^= 1;
        }
        else {
            f = false;
        }
    }
    if (f) {
        if (cur == 1) {
            check[u][1][0] = 1;
            dp[u][1][0] = cnt;
            if (mn != MAX) {
                cnt += mn;
                check[u][2][0] = 1;
                dp[u][2][0] = cnt;
            }
        }
        else {
            check[u][2][0] = 1;
            dp[u][2][0] = cnt;
            if (mn != MAX) {
                cnt += mn;
                check[u][1][0] = 1;
                dp[u][1][0] = cnt;
            }
        }
    }
    mn = MAX;
    cur = a[u], cnt = 0;
    f = true;
    for (auto to : g[u]) {
        if (to == p) continue;
        if (check[to][1][0] && check[to][1][1]) {
            if (dp[to][1][0] < dp[to][1][1]) {
                cnt += dp[to][1][0];
            }
            else {
                cnt += dp[to][1][1];
                cur ^= 1;
            }
            mn = min(mn, abs(dp[to][1][0] - dp[to][1][1]));
        }
        else if (check[to][1][0]) {
            cnt += dp[to][1][0];
        }
        else if (check[to][1][1]) {
            cnt += dp[to][1][1];
            cur ^= 1;
        }
        else {
            f = false;
        }
    }
    if (f) {
        if (cur == 1) {
            check[u][2][1] = 1;
            dp[u][2][1] = cnt + 1;
            if (mn != MAX) {
                check[u][1][1] = 1;
                cnt += mn;
                dp[u][1][1] = cnt + 1;
            }
        }
        else {
            check[u][1][1] = 1;
            dp[u][1][1] = cnt + 1;
            if (mn != MAX) {
                check[u][2][1] = 1;
                cnt += mn;
                dp[u][2][1] = cnt + 1;
            }
        }
    }
}

void slv() {
    cin >> n;
    for (int i = 0; i < n - 1; ++i) {
        int x, y;
        cin >> x >> y;
        g[x].pub(y);
        g[y].pub(x);
    }
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        dp[i][1][0] = dp[i][1][1] = dp[i][2][0] = dp[i][2][1] = MAX;
    }
    dfs();
    int ans = min(dp[1][2][0], dp[1][2][1]);
    if (ans == MAX) cout << "impossible";
    else cout << ans;
}

void cs() {
    int tstc = 1;
    //cin >> tstc;
    while (tstc--) {
        slv();
    }
}

void precalc() {
    return;
}

int main() {
    fastio();
    precalc();
    //precision(0);
    cs();
    return 0;
}

Compilation message (stderr)

xanadu.cpp: In function 'll range_sum(ll, ll)':
xanadu.cpp:97:21: warning: unused variable 'cnt' [-Wunused-variable]
   97 |     ll dif = a - 1, cnt = b - a + 1;
      |                     ^~~
xanadu.cpp: In function 'll bin_to_dec(std::string)':
xanadu.cpp:120:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |     for (int i = 0; i < s.size(); i++) {
      |                     ~~^~~~~~~~~~

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