Sorting and Searching in C++

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>

int main() {
    std::vector<int> marks = {66, 91, 78, 55, 84, 91};

    std::sort(marks.begin(), marks.end());                       // बढ़ता क्रम
    for (int m : marks) std::cout << m << " ";
    std::cout << "\n";

    std::sort(marks.begin(), marks.end(), std::greater<int>());  // घटता क्रम
    for (int m : marks) std::cout << m << " ";
    std::cout << "\n";

    int arr[] = {5, 2, 9, 1};
    std::sort(arr, arr + 4);                                     // साधारण arrays भी
    std::cout << arr[0] << " " << arr[3] << "\n";
    return 0;
}

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>

struct Student { std::string name; int marks; };

int main() {
    std::vector<Student> cls = {{"Ravi", 78}, {"Aman", 91}, {"Sara", 78}, {"Priya", 91}};

    // सबसे ज़्यादा marks पहले; बराबर हों तो नाम के alphabetical क्रम में
    std::sort(cls.begin(), cls.end(), [](const Student& a, const Student& b) {
        if (a.marks != b.marks) return a.marks > b.marks;
        return a.name < b.name;
    });

    int rank = 1;
    for (const auto& s : cls) std::cout << rank++ << ". " << s.name << " " << s.marks << "\n";
    return 0;
}

std::vector<int> rolls = {12, 7, 25, 3, 18};
auto it = std::find(rolls.begin(), rolls.end(), 25);
if (it != rolls.end())
    std::cout << "found at index " << (it - rolls.begin()) << "\n";   // 2

auto big = std::find_if(rolls.begin(), rolls.end(), [](int r) { return r > 15; });
std::cout << "first roll > 15: " << *big << "\n";                     // 25

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> marks = {35, 48, 55, 66, 66, 66, 78, 91};

    std::cout << std::boolalpha
              << "66 present? " << std::binary_search(marks.begin(), marks.end(), 66) << "\n"
              << "70 present? " << std::binary_search(marks.begin(), marks.end(), 70) << "\n";

    auto lo = std::lower_bound(marks.begin(), marks.end(), 66);   // पहला >= 66
    auto hi = std::upper_bound(marks.begin(), marks.end(), 66);   // पहला > 66
    std::cout << "66 appears " << (hi - lo) << " times, starting at index "
              << (lo - marks.begin()) << "\n";

    auto pos = std::lower_bound(marks.begin(), marks.end(), 70);
    std::cout << "70 would be inserted at index " << (pos - marks.begin()) << "\n";
    return 0;
}

void bubbleSort(std::vector<int>& a) {
    for (size_t i = 0; i + 1 < a.size(); i++) {
        bool swapped = false;
        for (size_t j = 0; j + 1 < a.size() - i; j++) {
            if (a[j] > a[j + 1]) {
                std::swap(a[j], a[j + 1]);
                swapped = true;
            }
        }
        if (!swapped) break;          // पहले से sorted: जल्दी रुको
    }
}

int binarySearch(const std::vector<int>& a, int key) {
    int low = 0, high = static_cast<int>(a.size()) - 1;
    while (low <= high) {
        int mid = low + (high - low) / 2;     // (low + high) के overflow से बचाव
        if (a[mid] == key) return mid;
        if (a[mid] < key)  low = mid + 1;
        else               high = mid - 1;
    }
    return -1;                                // नहीं मिला
}