Submission #1030785

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030785		Zicrus	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	785 ms	15196 KiB

shoes

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

typedef long long ll;

ll n;
ll pow2;
vector<ll> seg;

void segSet(ll id, ll val) {
    id += pow2;
    seg[id] = val;
    id /= 2;
    while (id) {
        seg[id] = seg[2*id] + seg[2*id+1];
        id /= 2;
    }
}

ll segGet(ll low, ll high) {
    low += pow2; high += pow2;
    ll ans = 0;
    while (low <= high) {
        if (low & 1) ans += seg[low++];
        if (!(high & 1)) ans += seg[high--];
        low /= 2; high /= 2;
    }
    return ans;
}

ll count_swaps(vector<int> a) {
    n = a.size() / 2;
    vector<vector<ll>> seenQNeg(n+10);
    vector<vector<ll>> seenQPos(n+10);
    ll res = 0;

    pow2 = 2ll << (ll)ceil(log2(n));
    seg = vector<ll>(2*pow2);

    for (int i = 0; i < a.size(); i++) {
        auto &q = a[i] < 0 ? seenQNeg[-a[i]] : seenQPos[a[i]];
        auto &pairQ = a[i] > 0 ? seenQNeg[a[i]] : seenQPos[-a[i]];
        if (pairQ.empty()) {
            q.insert(q.begin(), i);
        }
        else {
            ll id = pairQ.back();
            pairQ.pop_back();
            if (a[i] < 0) {
                res += abs(id - i) + segGet(id, i);
                segSet(i, -1);
                segSet(id, 1);
            }
            else {
                res += abs(id - i) - 1 + segGet(id, i);
                segSet(i, -1);
                segSet(id, 1);
            }
        }
    }
    return res;
}

Compilation message (stderr)

shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:41:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for (int i = 0; i < a.size(); i++) {
      |                     ~~^~~~~~~~~~

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