fast_input_output.cpp

auto init = []() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    return 'c';
}();

// second fast input output

static const int __ = []() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    return 0;
}();

int init = [] {
    ofstream out("user.out");
    cout.rdbuf(out.rdbuf());
    for (string str; getline(cin, str); cout << '\n') {
        if (str.find(',') == string::npos) {
            cout << str;
            continue;
        }
        stringstream ss(str);
        ss.ignore();
        int prev;
        ss >> prev;
        ss.ignore();
        cout << '[' << prev;
        for (int curr; ss >> curr; ss.ignore()) {
            cout << ',' << gcd(prev, curr) << ',' << curr;
            prev = curr;
        }
        cout << ']';
    }
    exit(0);
    return 0;
}();

// second fast input output method in c++

class Solution {
  public:
    static inline auto _ = [] {
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
        std::ofstream out("user.out", std::ios::out | std::ios::binary);
        out.rdbuf()->pubsetbuf(nullptr, 256);
        std::string s;
        std::noskipws(std::cin);
        while (std::getline(std::cin, s)) {
            int count = 0;
            bool inNum = false;
            for (char c : s) {
                if (std::isdigit(c) != 0) {
                    if (!inNum) {
                        ++count;
                        inNum = true;
                    }
                } else {
                    inNum = false;
                }
            }
            out << count << '\n';
        }
        std::skipws(std::cin);
        out.flush();
        exit(0);
        return 0;
    }();

    int countNodes(TreeNode *root) {
        if (root == nullptr)
            return 0;
        int left = countNodes(root->left);
        int right = countNodes(root->right);
        return 1 + left + right;
    }
};

// third approach .. this is the fastest in leetcode

int a[50001];
int init = [] {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ofstream out("user.out");
    for (string s; getline(cin, s);) {
        if (s.length() == 2) {
            out << "[]\n";
            continue;
        }
        int n = 0;
        for (int _i = 1, _n = s.length(); _i < _n; ++_i) {
            bool _neg = false;
            if (s[_i] == '-')
                ++_i, _neg = true;
            int v = s[_i++] & 15;
            while ((s[_i] & 15) < 10)
                v = v * 10 + (s[_i++] & 15);
            if (_neg)
                v = -v;
            a[n++] = v;
        }
        sort(a, a + n);
        out << '[' << a[0];
        for (int i = 1; i < n; ++i)
            out << ',' << a[i];
        out << "]\n";
    }
    out.flush();
    exit(0);
    return 0;
}();
const static auto initialize = [] {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    return nullptr;
}();