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在一个已经排序的非降序整形数组中，找到被搜索整数首次出现的位置，如果该整数出现多次的话。要求在log₂n次比交内完成。

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace ConsoleApplication3
{class Program{static void Main(string[] args){int[] a = new int[] { 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 6, 7, 7, 7, 7, 7 };for (int i = 1; i <= 7; ++i){Console.WriteLine(string.Format("Search {0}, Index: {1}, TestResult: {2}",i, biSearch(a, i),biSearch(a, i) == sequenceSearch(a, i)));}}static int biSearch(int[] a, int t){int n = a.Length;int l = 0; int b = n - 1;int f = -1;int m = -1;while (l <= b){m = (l + b) / 2;if (a[m] < t){l = m + 1;}else if (a[m] == t){f = m;b = m - 1;}else //a[m] > t
                {b = m - 1;}}return f;}static int sequenceSearch(int[] a, int t){for (int i = 0; i<a.Length; ++i){if (t == a[i]) return i;}return -1;}}
}