用C++实现折半查找和顺序查找

折半查找（二分查找）：

#include <iostream>
using namespace std;

int binarySearch(int arr[], int n, int x) {
    int l = 0, r = n - 1;
    while (l <= r) {
        int mid = l + (r - l) / 2;
        if (arr[mid] == x)
            return mid;
        else if (arr[mid] < x)
            l = mid + 1;
        else
            r = mid - 1;
    }
    return -1;
}

int main() {
    int arr[] = { 2, 3, 4, 10, 40 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int x = 10;
    int result = binarySearch(arr, n, x);
    (result == -1) ? cout << "Element is not present in array"
                   : cout << "Element is present at index " << result;
    return 0;
}

顺序查找：

#include <iostream>
using namespace std;

int linearSearch(int arr[], int n, int x) {
    for (int i = 0; i < n; i++) {
        if (arr[i] == x)
            return i;
    }
    return -1;
}

int main() {
    int arr[] = { 2, 3, 4, 10, 40 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int x = 10;
    int result = linearSearch(arr, n, x);
    (result == -1) ? cout << "Element is not present in array"
                   : cout << "Element is present at index " << result;
    return 0;
}