Submission #469437

#	Time	Username	Problem	Language	Result	Execution time	Memory
469437		cpp219	Swap (BOI16_swap)	C++14	100 / 100	859 ms	233680 KiB

swap

#include<bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
#define debug(y) cout<<y,exit(0)
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 2e5 + 9;
const ll inf = 1e9 + 7;

vector<ll> dp[N][18][2],tmp1,tmp2;
ll n,a[N];
bool need[N][18][2];

void Merge(vector<ll> &res,vector<ll> &a,vector<ll> &b){
    for (ll i = 0,j = 1;i < a.size();i += j,j *= 2){
        for (ll k = i;k < i + j && k < a.size();k++) res.push_back(a[k]);
        for (ll k = i;k < i + j && k < b.size();k++) res.push_back(b[k]);
    }
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "test"
    if (fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        //freopen(task".out","w",stdout);
    }
    cin>>n;
    for (ll i = 1;i <= n;i++) cin>>a[i];
    need[1][0][1] = 1;

    for (ll node = 1;node <= n/2;node++){
        for (ll i = 0;node >> i;i++){
            for (auto j : {0,1}){
                if (!need[node][i][j]) continue;
                ll p = ((node >> i + 1) << 1) + j;
                ll mn = min({a[p],a[node*2],a[node*2 + 1]});
                if (mn == a[node*2])
                    need[2*node][i + 1][j] = need[2*node + 1][0][1] = 1;
                else if (mn == a[p])
                    need[2*node][0][0] = need[2*node + 1][0][1] = 1;
                else
                    need[2*node][0][0] = need[2*node + 1][0][0] = 1,
                    need[2*node][i + 1][j] = need[2*node + 1][i + 1][j] = 1;
            }
        }
    }

    for (ll node = n;node;node--){
        for (ll i = 0;node >> i;i++){
            for (auto j : {0,1}){
                if (!need[node][i][j]) continue;

                ll p = ((node >> i + 1) << 1) + j;
                if (2*node > n) dp[node][i][j] = {a[p]};
                else if (2*node == n) dp[node][i][j] = {min(a[p],a[node*2]),max(a[p],a[node*2])};
                else{
                    ll mn = min({a[p],a[2*node],a[2*node + 1]});
                    if (mn == a[2*node + 1]){
                        tmp1 = tmp2 = {a[2*node + 1]};
                        Merge(tmp1,dp[2*node][0][0],dp[2*node + 1][i + 1][j]);
                        Merge(tmp2,dp[2*node][i + 1][j],dp[2*node + 1][0][0]);
                        dp[node][i][j] = min(tmp1,tmp2);
                    }
                    else{
                        dp[node][i][j] = {min(a[p],a[2*node])};
                        if (mn == a[p])
                            Merge(dp[node][i][j],dp[2*node][0][0],dp[2*node + 1][0][1]);
                        else
                            Merge(dp[node][i][j],dp[2*node][i + 1][j],dp[2*node + 1][0][1]);
                    }
                }
            }
        }
        if (2*node < n){
            for (ll i = 0;2*node >> i;i++){
                for (auto j : {0,1})
                    vector<ll>().swap(dp[2*node][i][j]),
                    vector<ll>().swap(dp[2*node + 1][i][j]);
            }
        }
    }
    for (auto i : dp[1][0][1]) cout<<i<<" ";
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
	* DON'T GET STUCK ON ONE APPROACH
*/

Compilation message (stderr)

swap.cpp: In function 'void Merge(std::vector<int>&, std::vector<int>&, std::vector<int>&)':
swap.cpp:17:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |     for (ll i = 0,j = 1;i < a.size();i += j,j *= 2){
      |                         ~~^~~~~~~~~~
swap.cpp:18:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |         for (ll k = i;k < i + j && k < a.size();k++) res.push_back(a[k]);
      |                                    ~~^~~~~~~~~~
swap.cpp:19:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |         for (ll k = i;k < i + j && k < b.size();k++) res.push_back(b[k]);
      |                                    ~~^~~~~~~~~~
swap.cpp: In function 'int main()':
swap.cpp:38:36: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   38 |                 ll p = ((node >> i + 1) << 1) + j;
      |                                  ~~^~~
swap.cpp:56:36: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   56 |                 ll p = ((node >> i + 1) << 1) + j;
      |                                  ~~^~~
swap.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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