Khóa học C++ từ cơ bản đến nâng cao

#include <iostream>
#include <set>

int main() {
    // 1. Khai báo một set chứa các số nguyên
    set<int> mySet;

    // 2. Thêm phần tử vào set
    mySet.insert(10);
    mySet.insert(5);
    mySet.insert(20);
    mySet.insert(5); // Phần tử này sẽ bị bỏ qua vì đã tồn tại

    // 3. Kích thước của set
    cout << "Kich thuoc cua set: " << mySet.size() << endl; // Output: 3

    // 4. Duyệt qua các phần tử (Chúng sẽ được sắp xếp!)
    cout << "Cac phan tu trong set: ";
    for (int element : mySet) {
        cout << element << " "; // Output: 5 10 20
    }
    cout << endl;

    // 5. Tìm kiếm một phần tử
    int valueToFind = 10;
    auto it = mySet.find(valueToFind); // find tra ve iterator hoac mySet.end() neu khong tim thay

    if (it != mySet.end()) {
        cout << valueToFind << " co ton tai trong set." << endl;
    } else {
        cout << valueToFind << " khong ton tai trong set." << endl;
    }

    int anotherValue = 15;
    if (mySet.count(anotherValue)) { // count() tra ve 1 neu ton tai, 0 neu khong
        cout << anotherValue << " co ton tai trong set (dung count)." << endl;
    } else {
        cout << anotherValue << " khong ton tai trong set (dung count)." << endl;
    }


    // 6. Xóa một phần tử
    mySet.erase(10);
    cout << "Kich thuoc cua set sau khi xoa 10: " << mySet.size() << endl; // Output: 2

    // Duyet lai de kiem tra
    cout << "Cac phan tu trong set sau khi xoa: ";
     for (int element : mySet) {
        cout << element << " "; // Output: 5 20
    }
    cout << endl;


    return 0;
}

#include <iostream>
#include <vector>
#include <set>

int main() {
    vector<int> numbers = {1, 2, 5, 3, 2, 4, 1, 5, 5, 3, 10, 8, 8, 12};

    // Khai bao mot set
    set<int> uniqueNumbers;

    // Them tat ca cac phan tu tu vector vao set
    for (int num : numbers) {
        uniqueNumbers.insert(num);
    }

    // Alternatively, initialize set directly from the vector range:
    // set<int> uniqueNumbers(numbers.begin(), numbers.end());


    // Kich thuoc cua set chinh la so luong phan tu duy nhat
    cout << "Vector ban dau: ";
    for(int num : numbers) cout << num << " ";
    cout << endl;

    cout << "So luong phan tu duy nhat: " << uniqueNumbers.size() << endl;

    // Bonus: In ra cac phan tu duy nhat (chung da duoc sap xep)
    cout << "Cac phan tu duy nhat (da sap xep): ";
    for (int num : uniqueNumbers) {
        cout << num << " ";
    }
    cout << endl;

    return 0;
}

#include <iostream>
#include <vector>
#include <set>
#include <chrono> // De do thoi gian

int main() {
    // Tao mot tap du lieu lon
    vector<int> largeData;
    for (int i = 0; i < 100000; ++i) {
        largeData.push_back(i * 2); // Cac so chan
    }
    // Them vai so le
    largeData.push_back(199999);
    largeData.push_back(55555);

    // Chuyen du lieu vao set de tim kiem nhanh
    set<int> dataSet(largeData.begin(), largeData.end());

    int valueToFind1 = 50000; // Co trong tap (so chan)
    int valueToFind2 = 50001; // Khong co trong tap (so le khac)
    int valueToFind3 = 199999; // Co trong tap (so le da them)


    // Kiem tra su ton tai dung set (O(log N))
    auto start_set = chrono::high_resolution_clock::now();

    if (dataSet.count(valueToFind1)) {
        cout << valueToFind1 << " co ton tai trong set." << endl;
    }
    if (!dataSet.count(valueToFind2)) {
        cout << valueToFind2 << " khong ton tai trong set." << endl;
    }
     if (dataSet.count(valueToFind3)) {
        cout << valueToFind3 << " co ton tai trong set." << endl;
    }

    auto end_set = chrono::high_resolution_clock::now();
    chrono::duration<double> elapsed_set = end_set - start_set;
    cout << "Thoi gian tim kiem dung set: " << elapsed_set.count() << " giay." << endl;


    // So sanh voi tim kiem tuyen tinh trong vector (O(N))
    // (Can include <algorithm>)
    /*
    auto start_vector = chrono::high_resolution_clock::now();
    bool found1 = false;
    for(int val : largeData) { if(val == valueToFind1) { found1 = true; break; } }
    if (found1) { cout << valueToFind1 << " co ton tai trong vector (tim tuyen tinh)." << endl; }
    // ... lam tuong tu cho cac gia tri khac ...
    auto end_vector = chrono::high_resolution_clock::now();
    chrono::duration<double> elapsed_vector = end_vector - start_vector;
    cout << "Thoi gian tim kiem dung vector (tuyen tinh): " << elapsed_vector.count() << " giay." << endl;
    */
    // Code tim kiem vector de so sanh nhanh se chay cham hon dang ke voi du lieu lon

    return 0;
}

#include <iostream>
#include <vector>
#include <set>
#include <algorithm> // Can thiet neu dung set_union

int main() {
    vector<int> vec1 = {1, 3, 5, 7, 9, 11};
    vector<int> vec2 = {2, 3, 4, 5, 6, 7, 8};

    // Cách 1: Dùng set de gom tat ca phan tu
    set<int> unionSet;

    // Them tat ca phan tu tu vec1
    for (int num : vec1) {
        unionSet.insert(num);
    }
    // Them tat ca phan tu tu vec2 (set tu loai bo trung lap)
    for (int num : vec2) {
        unionSet.insert(num);
    }

    cout << "Vector 1: "; for(int n : vec1) cout << n << " "; cout << endl;
    cout << "Vector 2: "; for(int n : vec2) cout << n << " "; cout << endl;


    cout << "Hop cua hai tap hop (dung set insert): ";
    for (int num : unionSet) {
        cout << num << " "; // Output: 1 2 3 4 5 6 7 8 9 11 (da sap xep)
    }
    cout << endl;

    // Cách 2: Dung thuat toan set_union (yeu cau du lieu dau vao phai duoc sap xep)
    // Chuyen vector sang set truoc de dam bao sap xep
    set<int> set1(vec1.begin(), vec1.end());
    set<int> set2(vec2.begin(), vec2.end());

    set<int> unionSetAlt;
    // set_union ghi ket qua vao iterator dau ra
    set_union(set1.begin(), set1.end(),
                   set2.begin(), set2.end(),
                   inserter(unionSetAlt, unionSetAlt.begin())); // Su dung inserter de them vao set

    cout << "Hop (dung set_union): ";
    for (int num : unionSetAlt) {
        cout << num << " "; // Output: 1 2 3 4 5 6 7 8 9 11
    }
    cout << endl;


    return 0;
}

#include <iostream>
#include <vector>
#include <set>
#include <algorithm> // Can thiet neu dung set_intersection

int main() {
    vector<int> vec1 = {1, 3, 5, 7, 9};
    vector<int> vec2 = {3, 6, 9, 12, 15};

    // Cách 1: Dung set de tim kiem hieu qua
    set<int> set1(vec1.begin(), vec1.end()); // Chuyen vec1 sang set de tim kiem nhanh O(log N)
    set<int> intersectionSet; // Set ket qua

    cout << "Vector 1: "; for(int n : vec1) cout << n << " "; cout << endl;
    cout << "Vector 2: "; for(int n : vec2) cout << n << " "; cout << endl;

    // Duyet qua vec2, kiem tra tung phan tu xem co trong set1 khong
    for (int num : vec2) {
        if (set1.count(num)) { // set1.count(num) tra ve 1 neu num co trong set1, 0 neu khong
             intersectionSet.insert(num); // Neu co, them vao set giao (set tu loai bo trung lap)
        }
    }

    cout << "Giao cua hai tap hop (dung set count): ";
    for (int num : intersectionSet) {
        cout << num << " "; // Output: 3 9 (da sap xep)
    }
    cout << endl;

    // Cách 2: Dung thuat toan set_intersection (yeu cau du lieu dau vao phai duoc sap xep)
     // Chuyen vector sang set truoc de dam bao sap xep
    set<int> set2(vec2.begin(), vec2.end());

    set<int> intersectionSetAlt;
    // set_intersection ghi ket qua vao iterator dau ra
    set_intersection(set1.begin(), set1.end(), // set1 da sap xep
                          set2.begin(), set2.end(), // set2 da sap xep
                          inserter(intersectionSetAlt, intersectionSetAlt.begin())); // Them vao set ket qua

    cout << "Giao (dung set_intersection): ";
    for (int num : intersectionSetAlt) {
        cout << num << " "; // Output: 3 9
    }
    cout << endl;


    return 0;
}

#include <iostream>
#include <vector>
#include <set>
#include <algorithm> // Neu muon copy tu set sang vector

int main() {
    vector<int> data = {10, 4, 8, 4, 12, 6, 8, 10, 2, 10, 6};

    cout << "Vector ban dau: ";
    for(int n : data) cout << n << " ";
    cout << endl;

    // Chuyen vector sang set
    set<int> uniqueSortedData(data.begin(), data.end());

    cout << "Cac phan tu duy nhat va da sap xep (tu set): ";
    for (int num : uniqueSortedData) {
        cout << num << " "; // Output: 2 4 6 8 10 12
    }
    cout << endl;

    // Neu ban muon ket qua tra ve la mot vector:
    vector<int> resultVector(uniqueSortedData.begin(), uniqueSortedData.end());

    cout << "Ket qua trong vector (duy nhat, da sap xep): ";
     for (int num : resultVector) {
        cout << num << " "; // Output: 2 4 6 8 10 12
    }
    cout << endl;


    return 0;
}