Submission #143454

#	Time	Username	Problem	Language	Result	Execution time	Memory
143454		ChrisT	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	414 ms	138476 KiB

shoes

#include<bits/stdc++.h>
#include "shoes.h"
using namespace std;
typedef long long ll;
const int MN = 2e5+2;
bool done[MN];
deque<int> inds[MN];
int bit[MN];
void update (int i, int v) {
    for (i++;i<MN;i+=i&-i)
        bit[i] += v;
}
int query (int i) {
    int ret = 0;
    for (i++;i>0;i^=(i&-i))
        ret += bit[i];
    return ret;
}
ll count_swaps (vector<int> s) {
    int n = s.size(); ll ret = 0;
    for (int i = 0; i < n; i++) {
        inds[s[i]+100000].push_back(i);
    }
    for (int i = 0; i < n; i++) if (!done[i]){
        int cur = s[i], ind = inds[100000-s[i]].front(); inds[100000-s[i]].pop_front(); inds[s[i]+100000].pop_front();
        done[ind] = 1;
        if (ind == i+1 && s[i] < 0) continue;
        ret += ind - i - (s[i] < 0) - query(ind) + query(i);
        update(ind,1);
    }
    return ret;
}

Compilation message (stderr)

shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:25:13: warning: unused variable 'cur' [-Wunused-variable]
         int cur = s[i], ind = inds[100000-s[i]].front(); inds[100000-s[i]].pop_front(); inds[s[i]+100000].pop_front();
             ^~~

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