Submission #741421

#	Time	Username	Problem	Language	Result	Execution time	Memory
741421		GrindMachine	Swap (BOI16_swap)	C++17	68 / 100	392 ms	91424 KiB

swap

// Om Namah Shivaya

#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;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

refs:
https://usaco.guide/problems/baltic-oi-2016swap/solution
hidden tcs

*/

const int MOD = 1e9 + 7;
const int N = 5e4 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<int> merge(int root, vector<int> v1, vector<int> v2) {
    vector<int> v3;
    v3.pb(root);

    int curr = 1;
    int ptr = 0;

    while (ptr < sz(v1) or ptr < sz(v2)) {
        rep(j, curr) {
            if (ptr < sz(v1)) {
                v3.pb(v1[ptr]);
            }
            ptr++;
        }

        ptr -= curr;

        rep(j, curr) {
            if (ptr < sz(v2)) {
                v3.pb(v2[ptr]);
            }
            ptr++;
        }

        curr *= 2;
    }

    return v3;
}

vector<int> a(N * 2, inf1);
int n;
vector<int> states[N];
vector<vector<int>> dp[N];

vector<int> go(int i, int j) {
    // lexi min bfs order of subtree i if a[i] = j
    if (i > n) return {};

    int j_ind = lower_bound(all(states[i]), j) - states[i].begin();
    if (!dp[i][j_ind].empty()) return dp[i][j_ind];

    int l = 2 * i;
    int r = 2 * i + 1;

    vector<int> res;

    if (j < a[l] and j < a[r]) {
        // no swaps
        res = merge(j, go(l, a[l]), go(r, a[r]));
    }
    else if (a[l] < j and a[l] < a[r]) {
        // swap root with left
        res = merge(a[l], go(l, j), go(r, a[r]));
    }
    else {
        // swap root with right
        auto v1 = merge(a[r], go(l, a[l]), go(r, j));

        // swap root with left and then with right
        auto v2 = merge(a[r], go(l, j), go(r, a[l]));

        res = min(v1, v2);
    }

    return dp[i][j_ind] = res;
}

void solve(int test_case)
{
    cin >> n;
    rep1(i, n) cin >> a[i];

    rep1(i, n) {
        for (int j = i; j; j >>= 1) {
            states[i].pb(a[j]);
            if (2 * j <= n) {
                states[i].pb(a[2 * j]);
            }
            if (2 * j + 1 <= n) {
                states[i].pb(a[2 * j + 1]);
            }
        }

        sort(all(states[i]));
        states[i].resize(unique(all(states[i])) - states[i].begin());

        int siz = sz(states[i]);
        dp[i] = vector<vector<int>>(siz);
    }

    auto ans = go(1, a[1]);

    trav(x, ans) cout << x << " ";
    cout << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

Compilation message (stderr)

swap.cpp: In function 'std::vector<int> merge(int, std::vector<int>, std::vector<int>)':
swap.cpp:71:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     while (ptr < sz(v1) or ptr < sz(v2)) {
      |                ^
swap.cpp:71:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     while (ptr < sz(v1) or ptr < sz(v2)) {
      |                                ^
swap.cpp:73:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |             if (ptr < sz(v1)) {
      |                     ^
swap.cpp:82:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   82 |             if (ptr < sz(v2)) {
      |                     ^

• Subtask 1: 10 / 10
• Subtask 2: 11 / 11
• Subtask 3: 27 / 27
• Subtask 4: 20 / 20
• Subtask 5: 0 / 32