Two-part lookup algorithm (recursive and non-recursive) __ algorithm

First of all, the binary search method.

The binary search method is to find a set of ordered numbers, pass the corresponding data, compare and find the same data as the original data, and find the corresponding array subscript, no return 1 is found;

The following example, in which ordered arrays are arranged in small to large order. (Thanks again to the Netizen's point)

The two-point search method was completed by non-recursive method. The Java code is shown below.

/**
     * Two points to find common implementations.
     * @param srcarray ordered array
     * @param key Find element
     * @return  not present return-1
     *
    /public static int Binsearch (int sr carray[], int key) {
        int mid;
        int start = 0;
        int end = Srcarray.length-1;
        while (start <= end) {
            mid = (End-start)/2 + start;
            if (Key < Srcarray[mid]) {
                end = mid-1;
            } else if (Key > Srcarray[mid]) {
                start = mid + 1;
            } E LSE {
                return mid;
            }
        }
        return-1;
    }

Recursive method is used to complete the two-point search algorithm. The code is shown below.

/**
     * Binary search recursive implementation.
     * @param srcarray  ordered array
     * @param start array low address subscript
     * @param end   Array High address subscript
     * @param key  find element
     * @return Lookup element does not exist return-1
     *
    /public static int binsearch (int srcarray[], int start, int end, int key) {
        int mid = (End-start)/2 + start;
        if (srcarray[mid] = = key) {
            return mid;
        }
        if (start >= end) {
            return-1;
        } else if (Key > Srcarray[mid]) {
            return Binsearch (Srcarray, mid + 1, End, key);
        } else if (Key < Srcarray[mid]) {
            return Binsearch (Srcarray, start, mid-1, key);
        }
        return-1;
    }

Recursive thinking is often used, more prominent programming problem-solving efficiency.

The call executes the main function, and the code is as follows.

public static void Main (string[] args) {
        int srcarray[] = {3,5,11,17,21,23,28,30,32,50,64,78,81,95,101};
        System.out.println (Binsearch (srcarray, 0, Srcarray.length-1, 222));
        System.out.println (Binsearch (srcarray,81));
    }

Say sorry here, before the code has a problem, oneself has been without modification, sin sin