210614_TIL

백준 알고리즘

백준 알고리즘 11725번 : 트리의 부모 찾기

#include <iostream>
#include <vector>
using namespace std;

#define MAX 100001

vector<int> v[MAX];
int parent[MAX];
bool visited[MAX];
int N;

void findParent(int x) {
    visited[x] = true;
    for (int i = 0; i < v[x].size(); i++) {
        int next = v[x][i];
        if (visited[next] == false) {
            parent[next] = x;
            findParent(next);
        }
    }
}

int main(int argc, const char* argv[]) {
    cin >> N;
    int a, b;
    for (int i = 1; i < N; i++) {
        cin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    findParent(1);

    for (int i = 2; i <= N; i++)
        cout << parent[i] << '\n';

    return 0;
}

백준 알고리즘 1991번 : 트리 순회

#include <iostream>
using namespace std;

int n;

struct node {
    char left;
    char right;
};

struct node arr[27];

void preOrder(char root) {
    if (root == '.')
        return;
    cout << root;
    preOrder(arr[root].left);
    preOrder(arr[root].right);
}

void inOrder(char root) {
    if (root == '.')
        return;
    inOrder(arr[root].left);
    cout << root;
    inOrder(arr[root].right);
}

void postOrder(char root) {
    if (root == '.')
        return;
    postOrder(arr[root].left);
    postOrder(arr[root].right);
    cout << root;
}

int main(int argc, const char* argv[]) {
    cin >> n;

    char a, b, c;

    for (int i = 1; i <= n; i++) {
        cin >> a >> b >> c;
        arr[a].left = b;
        arr[a].right = c;
    }

    preOrder('A');
    cout << "\n";
    inOrder('A');
    cout << "\n";
    postOrder('A');
    cout << "\n";

    return 0;
}