SDA - 2022-2023 - test5 - task 2

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

unordered_map<int, vector<int>> graph;
unordered_map<int, int> countNodes;
bool visited[100]{ false };

void dfs(int v) {
    visited[v] = true;
    auto neighbours = graph[v];

    for (int i = 0; i < neighbours.size(); i++) {
        if (!visited[neighbours[i]]) {
            dfs(neighbours[i]);
            countNodes[v] += countNodes[neighbours[i]] + 1;
        }
    }
}


int main() {
    int n, e, a, b;
    cin >> n >> e;
    for (int i = 0; i < e; i++) {
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    int res = 0;
    dfs(1);
    for (auto i : countNodes) {
        if (i.second % 2 != 0)
            res++;
    }
    cout << res;
    return 0;
}