BinarySearch

/*
Find an element in a sorted array:
1.Divide:Check middle element.
2.Conquer:Recursively search 1subarray.
3.Combine:Trivial.
*/

C++：

bool BinarySearch(int* a,int lhs,int rhs,int val) {
    if (lhs > rhs) {
        return false;
    }

    if (a[( lhs + rhs) / 2] == val) {
        return true;
    }
    else if (a[(lhs + rhs) / 2] < val) {
        BinarySearch(a, (lhs + rhs) / 2 + 1, rhs, val);
    }
    else {
        BinarySearch(a, lhs, (lhs + rhs) / 2 - 1, val);
    }

}

Text：

#include

bool BinarySearch(int* a,int lhs,int rhs,int val) {
    if (lhs > rhs) {
        return false;
    }

    if (a[( lhs + rhs) / 2] == val) {
        return true;
    }
    else if (a[(lhs + rhs) / 2] < val) {
        BinarySearch(a, (lhs + rhs) / 2 + 1, rhs, val);
    }
    else {
        BinarySearch(a, lhs, (lhs + rhs) / 2 - 1, val);
    }

}
int main() {
    int a[] = { 0,1,2,3,4,5,6,7,8,9 };
    std::cout << BinarySearch(a, 0, 9, 5) << std::endl;
    std::cout << BinarySearch(a, 0, 9, 10) << std::endl;
    return 0;
}