[Algorithm]Baekjoon 4386 :: 별자리 만들기

https://www.acmicpc.net/problem/4386

4386번: 별자리 만들기

 
 
using namespace std;
 
struct Node
{
    float distance;
    int node1;
    int node2;
};
 
bool cmp(const Node& a, const Node& b)
{
    return a.distance < b.distance;
}
 
int parents[100001] = { 0 };
 
int findParent(int node)
{
    if (node == parents[node]) return node;
    return parents[node] = findParent(parents[node]);
}
 
void unionParents(int a, int b)
{
    a = findParent(a);
    b = findParent(b);
 
    if (a < b) parents[b] = a;
    else parents[a] = b;
}
 
bool isSameParents(int a, int b)
{
    a = findParent(a);
    b = findParent(b);
 
    if (a == b) return true;
    return false;
}
 
int n;
vector<pair<float, float>> positions;
vector<Node> nodes;
 
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
 
    cin >> n;
 
    for (int i = 0; i < n; ++i)
    {
        parents[i] = i;
    }
    for (int i = 0; i < n; ++i)
    {
        float x, y;
        cin >> x >> y;
 
        positions.push_back({ x, y });
    }
    
    for (int i = 0; i < n; ++i)
    {
        for (int j = i + 1; j < n; ++j)
        {
            float xGap = powf(positions[i].first - positions[j].first, 2);
            float yGap = powf(positions[i].second - positions[j].second, 2);
            float distance = sqrt(xGap + yGap);
 
            nodes.push_back({ distance,i,j });
        }
    }
    
    sort(nodes.begin(), nodes.end(), cmp);
    float answer = 0.0f;
 
    for (int i = 0; i < nodes.size(); ++i)
    {
        if (isSameParents(nodes[i].node1, nodes[i].node2) == false)
        {
            unionParents(nodes[i].node1, nodes[i].node2);
            answer += nodes[i].distance;
        }
    }
 
    printf("%.2f", answer);
}
 

 

전형적인 MST문제. 소수점 둘째자리수까지만 출력해줘야 하는것을 잊지말자.