Submission #318769

#TimeUsernameProblemLanguageResultExecution timeMemory
318769penguin71630Arranging Shoes (IOI19_shoes)C++14
0 / 100
1 ms492 KiB
#include "shoes.h"
#include <bits/stdc++.h>

#define flag(_a) cout << "Still alive at flag " << _a << '\n';
#define dbg(_a, _b) cout << "var " << _a << " -> " << _b << '\n';
#define dbg_itv(_l, _r, _val) cout << "itv (" << _l << ", " << _r << ") -> " << _val << '\n';
using namespace std;

typedef long long ll;
const int maxn = 2e5 + 2;

ll n;
ll bit[maxn];
vector<queue<int> > L, R;

ll lb(ll x) {return x & (-x);}

void build() {
    for (ll i = 1; i <= n; i++) {
        bit[i] = (i - (i-lb(i)+1) + 1);
    }
}

void modify(ll x) {
    for (; x <= n; x += lb(x)) {
        bit[x]--;
    }
}

ll qry(ll x) {
    ll sum = 0;
    for (; x > 0; x -= lb(x)) {
        sum += bit[x];
    }
    return sum;
}

ll count_swaps(vector<int> s) {
    n = (int)s.size();
    L.resize(n/2+1);
    R.resize(n/2+1);
	for (int i = 0; i < n; i++) {
	    if (s[i] < 0) L[-s[i]].push(i+1);
	    else R[s[i]].push(i+1);
	}
    build();

	ll ans = 0;
    for (int i = 1; i <= n; i++) {
        if (qry(i)) {
            if (s[i] < 0) {
                int lpos = i, rpos = R[-s[i]].front();
                L[-s[i]].pop(), R[-s[i]].pop();

                ans += qry(rpos - 1) - qry(lpos);
                modify(lpos), modify(rpos);
            } else {
                int lpos = L[s[i]].front(), rpos = i;
                L[s[i]].pop(), R[s[i]].pop();

                ans += qry(lpos - 1) - qry(rpos - 1);
                modify(lpos), modify(rpos);
            }
        }
    }

	return ans;
}
/*
2
2 1 -1 -2
 */
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