Submission #965375

#	Time	Username	Problem	Language	Result	Execution time	Memory
965375		Syrius	Arranging Shoes (IOI19_shoes)	C++14	0 / 100	411 ms	546628 KiB

shoes

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

// #define int long long
#define ll long long
#define ff first
#define ss second
#define pint pair < int , int >
#define fast ios_base::sync_with_stdio(NULL); cin.tie(NULL)

const int inf = 1e9 + 9;
const int mxn = 2e5 + 2;
const int mod = 1e9 + 7;

int fn[mxn];
void update(int x , int v) {
	for (; x <= mxn; x += x&-x) {
		fn[x] += v;
	}
}

int query(int l , int r) {
	int ans = 0;
	l--;
	for (; r > 0; r -= r&-r) ans += fn[r];
	for (; l > 0; l -= l&-l) ans -= fn[l];
}

ll count_swaps(vector < int > v) {

	int n = v.size() / 2;
	bool b[2*n];

	queue < int > left[mxn] , right[mxn];
	for (int i = 0; i < 2 * n; i++) {
		if (v[i] < 0) left[v[i]].push(i);
		else right[v[i]].push(i);
		update(i+1 , 1);
	}

	int ans = 0;
	for (int i = 0; i < 2*n; i++) {
		if (b[i]) continue;
		int id;
		if (b[i] < 0) {
			id = right[b[i]].front();
			right[b[i]].pop();
			ans += query(i+2 , id);
			update(id+1 , -1);
		} else {
			id = left[b[i]].front();
			left[b[i]].pop();
			ans += query(i+2 , id) + 1;
			update(id+1 , -1);
		}
	}
	
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'int query(int, int)':
shoes.cpp:28:1: warning: no return statement in function returning non-void [-Wreturn-type]
   28 | }
      | ^
shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:46:12: warning: comparison of constant '0' with boolean expression is always false [-Wbool-compare]
   46 |   if (b[i] < 0) {
      |       ~~~~~^~~
shoes.cpp:37:26: warning: array subscript -1 is below array bounds of 'std::queue<int> [200002]' [-Warray-bounds]
   37 |   if (v[i] < 0) left[v[i]].push(i);
      |                 ~~~~~~~~~^
shoes.cpp:37:26: warning: array subscript -1 is below array bounds of 'std::queue<int> [200002]' [-Warray-bounds]
shoes.cpp:37:26: warning: array subscript -1 is below array bounds of 'std::queue<int> [200002]' [-Warray-bounds]

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