Submission #73086

#	Time	Username	Problem	Language	Result	Execution time	Memory
73086		Benq	Ranklist Sorting (BOI07_sorting)	C++14	100 / 100	17 ms	8496 KiB

sorting

#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;

int n;
vi s;

void compress() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n; s.resize(n);
    map<int,int> m;
    F0R(i,n) {
        cin >> s[i];
        m[s[i]] = 0;
    }
    int co = 0;
    for (auto& a: m) a.s = co++;
    for (int& i: s) i = n-1-m[i];
}

int notInv(vi st) {
    int ret = 0;
    F0R(i,sz(st)) FOR(j,i+1,sz(st)) if (st[i] < st[j]) ret ++;
    return ret;
}

int comb(int x) { return x*(x-1)/2; }


pair<int,vpi> test(vi z) {
    vpi S; F0R(i,sz(s)) S.pb({s[i],1});
    int lst = -1, notFixed = 0, getFixed = 0;
    vi st;
    int c = 0;
    vi zz;
    F0R(i,n) {
        if (find(all(z),S[i].f) != z.end()) {
            st.pb(S[i].f);
            S[i].s = 0;
            notFixed ++;
            getFixed += c;
        } else {
            if (S[i].f < lst) return {MOD,{}};
            lst = S[i].f;
            c ++;
            zz.pb(S[i].f);
        }
    }
    for (int i: st) for (int j: zz) if (i > j) getFixed ++;
    // cout << notInv(st)+comb(notFixed)+2*notFixed+getFixed << "\n";
    vpi v;
    int cur = 0;
    F0Rd(i,n) {
        int ind = 0; while (S[ind].f != i) ind ++;
        if (S[ind].s) continue;
        cur += ind+1; S.erase(S.begin()+ind);
        int lst = 0;
        F0R(j,n-1) if (S[j].s && S[j].f < i) lst = j+1;
        cur += lst+1; S.insert(S.begin()+lst,{i,1});
        v.pb({ind+1,lst+1});
    }
    return {cur,v};
}

pi dp[1001][1001];
int pos[1001];

void MN(pi& a, pi b) { a = min(a,b); }

int main() {
    compress();
    s.pb(n);
    F0R(i,sz(s)) pos[s[i]] = i;
    F0R(i,n+1) F0R(j,n+1) dp[i][j] = {MOD,MOD};
    dp[n][n] = {0,MOD};
    
    F0Rd(i,n) {
        int a = 1; F0R(j,pos[i]) if (s[j] < i) a ++;
        a ++;
        F0R(j,n+1) { 
            if (s[j] < i) a ++;
            MN(dp[i][j],{dp[i+1][j].f+a,j});
        }
        
        int c = 0;
        FOR(k,pos[i]+1,n+1) {
            MN(dp[i][pos[i]],{dp[i+1][k].f+c,k});
            c += max(i-s[k],0);
        }
    }
    int bes = 0;
    F0R(i,n+1) if (dp[0][i].f < dp[0][bes].f) bes = i;
    pi cur = {0,bes};
    vi move;
    while (cur.f < n) {
        // cout << "OOPS " << cur.f << " " << cur.s << "\n";
        if (dp[cur.f][cur.s].s == cur.s) move.pb(cur.f);
        cur = {cur.f+1,dp[cur.f][cur.s].s};
    }
    /*for (int i: move) cout << i << " ";
    cout << "\n";*/
    auto a = test(move);
    cout << sz(a.s) << "\n";
    for (auto x: a.s) {
        cout << x.f << " " << x.s << "\n";
    }
}

/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( ) 
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
* if you have no idea just guess the appropriate well-known algo instead of doing nothing :/
*/

• Subtask 1: 100 / 100