Submission #124037

#	Time	Username	Problem	Language	Result	Execution time	Memory
124037		mechfrog88	City Mapping (NOI18_citymapping)	C++14	57 / 100	121 ms	13068 KiB

citymapping

#include "citymapping.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

struct node{
	ll a,b,w;
	bool operator <(const node& rhs) const{
		return w < rhs.w;
	}
};

vector <ll> id;

ll find(ll i){
	if (id[i] < 0) return i;
	return id[i] = find(id[i]);
}

void unio(ll i,ll j){
	ll a = find(i);
	ll b = find(j);
	if (a == b) return;
	if (id[b] < id[a]) swap(a,b);
	id[a] += id[b];
	id[b] = a;
}


void find_roads(int n, int q, int a[], int b[], int w[]) {
	vector <node> arr;
	if (q == 12000){
		for (int z=2;z<=n;z++){
			node temp;
			temp.a = 1; temp.b = z; temp.w = get_distance(1,z);
			arr.push_back(temp); 
		}
		sort(arr.begin(),arr.end());
		ll left = 0;
		ll right = 0;
		ll leftpos = 1;
		ll rightpos = 1;
		ll c = 0;
		for (int z=0;z<n-1;z++){
			ll temp = get_distance(leftpos,arr[z].b);
			if (left+temp == arr[z].w){
				left += temp;
				a[c] = leftpos;
				b[c] = arr[z].b;
				w[c] = temp;
				leftpos = arr[z].b;
				c++;
				continue;
			}
			temp = get_distance(rightpos,arr[z].b);
			if (right+temp == arr[z].w){
				right += temp;
				a[c] = rightpos;
				b[c] = arr[z].b;
				w[c] = temp;
				rightpos = arr[z].b;
				c++;
				continue;
			}
		}
		return;
	}

	for (int z=1;z<=n;z++){
		for (int x=z+1;x<=n;x++){
			node temp;
			temp.a = z; temp.b = x; temp.w = get_distance(z,x);
			arr.push_back(temp);
		}
	}
	id.resize(n+1,-1);
	sort(arr.begin(),arr.end());
	vector <ll> count(n+1,0);
	ll c = 0;
	for (int z=0;z<arr.size();z++){
		if (count[arr[z].a] >= 3 || count[arr[z].b] >= 3) continue;
		ll i = find(arr[z].a);
		ll j = find(arr[z].b);
		if (i == j) continue;
		unio(i,j);
		a[c] = arr[z].a;
		b[c] = arr[z].b;
		w[c] = arr[z].w;
		count[arr[z].a]++;
		count[arr[z].b]++;
		c++;
	}
	return;
}

Compilation message (stderr)

citymapping.cpp: In function 'void find_roads(int, int, int*, int*, int*)':
citymapping.cpp:80:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int z=0;z<arr.size();z++){
               ~^~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 16 / 16
• Subtask 3: 13 / 13
• Subtask 4: 19 / 19
• Subtask 5: 0 / 43