Submission #1072324

#	Time	Username	Problem	Language	Result	Execution time	Memory
1072324		c2zi6	Thousands Islands (IOI22_islands)	C++17	8.40 / 100	31 ms	7748 KiB

islands

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#include "islands.h"
 
int n, m;
VVPI gp;

stack<PII> st;
VI onstack, vis;
VI path, cycle;

bool dfs(int u = 0, int pi = -1) {
    for (auto[v, i] : gp[u]) if (i != pi) {
        if (onstack[v]) {
            cycle.pb(i);
            while (st.size()) {
                if (st.top().ff == v) break;
                cycle.pb(st.top().ss);
                st.pop();
            }
            while (st.size()) {
                path.pb(st.top().ss);
                st.pop();
            }
            reverse(all(path));
            reverse(all(cycle));
            /*for (int x : path) cout << x << " "; cout << "| ";*/
            /*for (int x : cycle) cout << x << " "; cout << endl;*/
            return true;
        }
        if (vis[v]) continue;
        vis[v] = true;
        onstack[v] = true;
        st.push({v, i});
        if (dfs(v, i)) return true;
        onstack[v] = false;
    }
    return false;
}

VI rev(VI a) {
    reverse(all(a));
    return a;
}

int myus(int x) {
    int type = !(x%2);
    return x/2*2+type;
}

variant<bool, VI> find_journey(int N, int M, VI U, VI V) {
    n = N;
    m = M;
    gp = VVPI(n);
    rep(i, m) gp[U[i]].pb({V[i], i});
    onstack = vis = VI(n);
    if (dfs());
    else return false;
    VI ans;
    for (int x : path) ans.pb(x);
    for (int x : cycle) ans.pb(x);
    for (int x : rev(path)) ans.pb(x);
    path[0] = myus(path[0]);
    for (int x : path) ans.pb(x);
    for (int x : rev(cycle)) ans.pb(x);
    for (int x : rev(path)) ans.pb(x);
    return ans;
}
 
 
 
 

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 0 / 45