查找

一.二分查找

#include<iostream>
using namespace std;

template <typename T>
int BinarySearch(T A[], int start, int end, T k)
{
    if (A == NULL || start < 0 || end < 0 || start > end)
    {
        return -1;
    }
    
    int mid = (start + end) / 2;
    if (A[mid] == k)
    {
        return mid;
    }
    else if (A[mid] > k)
    {
        return BinarySearch(A, start, mid - 1, k);
    }
    else
    {
        return BinarySearch(A, mid + 1, end, k);
    }
}

int main()
{
    double A[] = { -10, -2.1, 1.1, 2.6, 3, 3, 4, 6};
    cout << BinarySearch(A, 0, 7, 6.0); // 7

    cout << endl;
    return 0;
}