Search a sorted integer array for the target value in O(log N) time. - CSharp System

CSharp examples for System:Array Search

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Description

Search a sorted integer array for the target value in O(log N) time.

Demo Code

// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
using System.Diagnostics;
using System;/*from w  ww  .  j  av  a  2  s.c o m*/

public class Main{
        /// <summary>
        /// Search a sorted integer array for the target value in O(log N) time.
        /// </summary>
        /// <param name="array">The array of integers which must be sorted in ascending order.</param>
        /// <param name="value">The target value.</param>
        /// <returns>An index in the array pointing to the position where <paramref name="value"/> should be
        /// inserted in order to maintain the sorted order. All values to the right of this position will be
        /// strictly greater than <paramref name="value"/>. Note that this may return a position off the end
        /// of the array if all elements are less than or equal to <paramref name="value"/>.</returns>
        internal static int BinarySearchUpperBound(this int[] array, int value)
        {
            int low = 0;
            int high = array.Length - 1;

            while (low <= high)
            {
                int middle = low + ((high - low) >> 1);
                if (array[middle] > value)
                {
                    high = middle - 1;
                }
                else
                {
                    low = middle + 1;
                }
            }

            return low;
        }
}

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