英文:
Sort only the odd elements of an array
问题
I want to sort only the odd elements of an array, leaving the even elements unchanged.
I have created the below using LINQ queries, but get an error on this line:
.Select(x => x.value % 2 == 1 ? x.value : dictionary[x.index])
The error is due to there not being an item in the dictionary with key '2'. I.e. the dictionary[x.index] term in the if statement is being evaluated when the criteria for the if statement is false (i.e. when x.value is even).
public class Kata{public static int[] SortArray(int[] array){var dictionary = array.Select((value, index) => new { value, index }).Where(x => x.value % 2 == 1).OrderBy(x => x.value).ToDictionary(x => x.index, x => x.value);var output = array.Select((value, index) => new { value, index }).Select(x => x.value % 2 == 1 ? x.value : dictionary[x.index]).ToArray();return new int[1];}}public class Program{static void Main(string[] args){Console.WriteLine(Kata.SortArray(new int[] { 5, 3, 2, 8, 1, 4 }));}}
英文:
I want to sort only the odd elements of an array, leaving the even elements unchanged.
I have created the below using LINQ queries, but get an error on this line:
.Select(x => x.value % 2 == 1 ? x.value : dictionary[x.index])
The error is due to there not being an item in the dictionary with key '2'. I.e. the dictionary[x.index] term in the if statement is being evaluated when the criteria for the if statement is false (i.e. when x.value is even).
public class Kata{public static int[] SortArray(int[] array){var dictionary = array.Select((value, index) => new { value, index }).Where(x => x.value % 2 == 1).OrderBy(x => x.value).ToDictionary(x => x.index, x => x.value);var output = array.Select((value, index) => new { value, index }).Select(x => x.value % 2 == 1 ? x.value : dictionary[x.index]).ToArray();return new int[1];}}public class Program{static void Main(string[] args){Console.WriteLine(Kata.SortArray(new int[] { 5, 3, 2, 8, 1, 4 }));}}
答案1
得分: 1
你可以提取奇数项，对它们进行排序，最后将它们放回：
int[] array = new int[] { 5, 3, 2, 8, 1, 4};// 提取并排序奇数项using var odd = array.Where(item => item % 2 != 0).OrderBy(item => item).GetEnumerator();for (int i = 0; i < array.Length; ++i)if (array[i] % 2 != 0 && odd.MoveNext())array[i] = odd.Current;
请注意，检查奇数应该是 item % 2 != 0，而不是 item % 2 == 1，因为余数 % 在负数 item 上返回 -1。
英文:
You can extract odd items, sort them, and finally put them back:
int[] array = new int[] { 5, 3, 2, 8, 1, 4};// odd items extracted and sortedusing var odd = array.Where(item => item % 2 != 0).OrderBy(item => item).GetEnumerator();for (int i = 0; i < array.Length; ++i)if (array[i] % 2 != 0 && odd.MoveNext())array[i] = odd.Current;
Please, note that checking for odd should be item % 2 != 0, not item % 2 == 1, since remainder % returns -1 on negative item.
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