方法一:递归算法
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/// <summary> /// 一列数的规则如下: 1、1、2、3、5、8、13、21、34求第30位数是多少, 用递归算法实现。(C#语言) /// </summary> /// <param name="pos"></param> /// <returns></returns> public int GetNumberAtPos( int pos) { if (pos==0||pos==1) { return 1; } int res = GetNumberAtPos(pos - 1) + GetNumberAtPos(pos - 2); return res; } |
方法二:不用递归
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using System; using System.Collections; using System.Collections.Generic; using System.Text; namespace Test { public class Class1 { private ArrayList list = new ArrayList(); public Class1() { } public Class1( int num) : base () { int i; for (i = 1; i <= num; i++) { list.Add(Calculation(i)); } } private int Calculation( int num) { if (num == 1 || num == 2) return 1; else return Convert.ToInt32(list[num - 2]) + Convert.ToInt32(list[num - 3]); } public int Calculation() { return Convert.ToInt32(list[list.Count - 1]); } } public class test { public static void Main() { int j; int num; for (j = 1; j < 100; j++) { Console.WriteLine( "你要计算第多少位:" ); string readstr; readstr = Console.ReadLine(); if (! string .IsNullOrEmpty(readstr)) { if ( int .TryParse(readstr, out num)) { if (num < 1) continue ; else { Class1 c1 = new Class1(num); Console.WriteLine(c1.Calculation()); } } else { continue ; } } else { break ; } } } } } |
方法三:用循环实现
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public long getNumber( int pos) { long one = 1; long two = 1; if (pos == 0 || pos == 1) { return 1; } int i = 3; long sum = 1; while (i <= pos) { sum = one + two; one = two; two = sum; i++; } return sum; } |
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