Submission #740996

#	Time	Username	Problem	Language	Result	Execution time	Memory
740996		GrindMachine	Swap (BOI16_swap)	C++17	21 / 100	21 ms	24560 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

*/

const int MOD = 1e9 + 7;
const int N = 1e3 + 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> merge(int val, vector<int> l, vector<int> r) {
    vector<int> ret;
    ret.pb(val);
    for (int i = 0, j = 1; i < l.size(); i += j, j <<= 1) {
        for (int k = i; k < i + j && k < l.size(); k++) ret.push_back(l[k]);
        for (int k = i; k < i + j && k < r.size(); k++) ret.push_back(r[k]);
    }
    return ret;
}

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

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

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

    // no swaps
    auto v1 = merge(j, go(l, a[l]), go(r, a[r]));

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

    // swap root with right
    auto v3 = merge(a[r], go(l, a[l]), go(r, j));

    // swap root with left and then with right
    auto v4 = merge(a[r], go(l, j), go(r, a[l]));

    vector<int> res = min({v1, v2, v3, v4});

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

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

    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:96:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |     for (int i = 0, j = 1; i < l.size(); i += j, j <<= 1) {
      |                            ~~^~~~~~~~~~
swap.cpp:97:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |         for (int k = i; k < i + j && k < l.size(); k++) ret.push_back(l[k]);
      |                                      ~~^~~~~~~~~~
swap.cpp:98:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |         for (int k = i; k < i + j && k < r.size(); k++) ret.push_back(r[k]);
      |                                      ~~^~~~~~~~~~

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