Submission #832106

#	Time	Username	Problem	Language	Result	Execution time	Memory
832106		maomao90	Arranging Shoes (IOI19_shoes)	C++17	85 / 100	17 ms	2644 KiB

shoes

// I can do all things through Christ who strengthens me
// Philippians 4:13

#include "shoes.h"
#include "bits/stdc++.h"
using namespace std;

#define REP(i, j, k) for (int i = j; i < (k); i++)
#define RREP(i, j, k) for (int i = j; i >= (k); i--)

template <class T>
inline bool mnto(T &a, const T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T &a, const T b) {return a < b ? a = b, 1 : 0;}

typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define SZ(x) (int) x.size()
#define ALL(x) x.begin(), x.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vll;
typedef tuple<int, int, int> iii;
typedef vector<iii> viii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

const int INF = 1000000005;
const ll LINF = 1000000000000000005;
const int MAXN = 200005;

int n;

namespace st2 {
    ll count_swaps(vi s) {
        vi lp, rp;
        REP (i, 0, 2 * n) {
            if (s[i] < 0) {
                lp.pb(i);
            } else {
                rp.pb(i);
            }
        }
        ll ans = 0;
        while (!s.empty()) {
            int id = -1;
            RREP (i, SZ(s) - 2, 0) {
                if (abs(s[i]) == abs(s.back()) && s[i] != s.back()) {
                    id = i;
                    break;
                }
            }
            assert(id != -1);
            ans += SZ(s) - id - (s.back() < 0 ? 1 : 2);
            s.pop_back();
            s.erase(s.begin() + id);
        }
        return ans;
        /*
        vi id(n);
        iota(ALL(id), 0);
        do {
            ll cur = 0;
            REP (i, 0, n) {
                REP (j, i + 1, n) {
                    if (id[i] > id[j]) {
                        cur++;
                    }
                }
            }
            vector<bool> vis(n, 0);
            REP (i, 0, n) {
                REP (j, 0, n) {
                    if (vis[j] || abs(s[lp[i]]) != abs(s[rp[j]])) {
                        continue;
                    }
                    vis[j] = 1;

                }
            }
        } while (next_permutation(ALL(id)));
        */
    }
}

namespace st3 {
    ll count_swaps(vi s) {
        int ptr = 0;
        ll ans = 0;
        REP (i, 0, 2 * n) {
            if (s[i] < 0) {
                ans += abs(i - ptr);
                ptr += 2;
            }
        }
        return ans;
    }
}

ll count_swaps(vi s) {
    n = SZ(s) / 2;
    bool st3 = 1;
    REP (i, 1, 2 * n) {
        if (abs(s[i]) != abs(s[i - 1])) {
            st3 = 0;
        }
    }
    bool st2 = n <= 1000;
    if (st2) {
        return st2::count_swaps(s);
    } else if (st3) {
        return st3::count_swaps(s);
    }
    ll ans = 0;
    REP (i, 0, n) {
        ans += i;
    }
	return ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 15