제출 #896038

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
896038		niter	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	206 ms	43196 KiB

Main

#include <bits/stdc++.h>
#define loop(i,a,b) for(int i = (a); i < (b); i ++)
#define pb push_back
#define ins insert
#define pii pair<int,int>
#define ff first
#define ss second
#define BAE(x) x.begin(), x.end()
#define op(x) cerr << #x << " = " << x << endl;
#define opa(x) cerr << #x << " = " << x << ", ";
#define ops(x) cerr << x;
#define opse(x) cerr << x << endl;
#define spac cerr << ' ';
#define entr cerr << endl;
#define STL(x) cerr << #x << " : "; for(auto &qwe:x) cerr << qwe << ' '; cerr << endl;
#define ARR(x, nnn) cerr << #x << " : "; loop(qwe,0,nnn) cerr << x[qwe] << ' '; cerr << endl;
#define bye exit(0);
using namespace std;
mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
inline int rng(int l, int r){ return uniform_int_distribution<int>(l, r)(RNG); }
ostream& operator<<(ostream& os, pii A){ os << "[" << A.ff << ", " << A.ss << "]"; }

const int mxn = (int)(2e5) + 10;

int val[mxn], dep[mxn];
long long dp[mxn];
bool vis[mxn];
vector<int> E[mxn];
int jump[mxn][18]; // [v, x] => from v, jump 2^x times

void dfs(int v, int par, int dis){
    dep[v] = dis;
    for(auto &i:E[v]){
        if(i == par) continue;
        dfs(i, v, dis + 1);
        jump[i][0] = v;
    }
}

void init_lca(int n){
    jump[0][0] = 0;
    dfs(0, -1, 0);
    loop(j,1,18){
        loop(i,0,n){
            jump[i][j] = jump[(jump[i][j-1])][j-1];
        }
    }
}

inline int lca(int a, int b){
    if(dep[a] > dep[b]) swap(a, b);
    int diff = dep[b] - dep[a];
    loop(i,0,18){
        if((diff >> i) & 1) b = jump[b][i];
    }
    if(a == b) return b;
    for(int i = 17; i >= 0; i--){
        if(jump[a][i] != jump[b][i]){
            a = jump[a][i];
            b = jump[b][i];
        }
    }
    a = jump[a][0];
    b = jump[b][0];
    return b;
}

int fa[mxn], sz[mxn], comp_mx[mxn];
int get_father(int v){
    if(fa[fa[v]] == fa[v]) return fa[v];
    return fa[v] = get_father(fa[v]);
}
inline void merg(int x, int y){
    x = get_father(x);
    y = get_father(y);
    if(x == y) return;
    if(sz[x] < sz[y]) swap(x, y);
    sz[x] += sz[y];
    comp_mx[x] = (val[comp_mx[x]] > val[comp_mx[y]]) ? comp_mx[x] : comp_mx[y];
    fa[y] = x;
}
inline int get_comp_max(int v){
    return comp_mx[get_father(v)];
}

int main(){
    ios::sync_with_stdio(false); cin.tie(0);
    int n; cin >> n;
    loop(i,0,n) cin >> val[i];
    loop(i,0,n-1){
        int u, v;
        cin >> u >> v;
        u--; v--;
        E[u].pb(v);
        E[v].pb(u);
    }
    init_lca(n);
    loop(i,0,n){
        fa[i] = comp_mx[i] = i;
        sz[i] = 1;
    }
    vector<pii> ord_sort;
    loop(i,0,n){
        ord_sort.pb({val[i], i});
    }
    sort(BAE(ord_sort));
    vector<int> ord;
    for(auto &i:ord_sort) ord.pb(i.ss);
    long long ans = 0;
    for(auto &i:ord){
        vis[i] = true;
        for(auto &j:E[i]){
            if(vis[j]){
                int son = get_comp_max(j);
                dp[i] = max(dp[i], dp[son] + (dep[i] + dep[son] - dep[lca(i, son)] * 2));
                merg(i, j);
            }
        }
    }
    loop(i,0,n) ans = max(ans, dp[i]);
    cout << ans << '\n';
}
/*
10
5 1 10 3 8 2 4 7 9 6
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
*/

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In function 'std::ostream& operator<<(std::ostream&, std::pair<int, int>)':
Main.cpp:21:84: warning: no return statement in function returning non-void [-Wreturn-type]
   21 | ostream& operator<<(ostream& os, pii A){ os << "[" << A.ff << ", " << A.ss << "]"; }
      |                                                                                    ^

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26