Created
December 26, 2017 04:14
-
-
Save jianminchen/3c89e9bb8aca78aaaada9e9b8067e226 to your computer and use it in GitHub Desktop.
Follow up - clean code after mock interview practice - line 26 - 33
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
using System; | |
class Solution | |
{ | |
public static int GetDifferentNumber(int[] arr) // [1, 3, 2, 100] | |
{ | |
if(arr == null || arr.Length == 0) //false | |
{ | |
return 0; | |
} | |
scanArraySwap(arr); | |
return findFirstMissingNumber(arr); | |
} | |
private static void scanArraySwap(int[] arr) | |
{ | |
int length = arr.Length; // 4 | |
int index = 0; | |
while(index < length) /// [100, 1, 2, 3] | |
{ | |
var number = arr[index]; // 1 | |
var isLessThanSize = number < length; // true, false | |
if(isLessThanSize && index != arr[index]) | |
{ | |
swap(arr, index, arr[index]); // 0, 1; 0, 3 | |
} | |
else | |
{ | |
index ++; // 1 | |
} | |
} | |
} | |
private static int findFirstMissingNumber(int[] arr) | |
{ | |
int length = arr.Length; | |
for(int i = 0; i < length; i++) | |
{ | |
if(arr[i] != i) | |
{ | |
return i; | |
} | |
} | |
return length; | |
} | |
private static void swap(int[] arr, int pos1, int pos2) | |
{ | |
int tmp = arr[pos1]; | |
arr[pos1] = arr[pos2]; | |
arr[pos2] = tmp; | |
} | |
static void Main(string[] args) | |
{ | |
Console.WriteLine(GetDifferentNumber(new int[]{0, 1, 2, 3})) ; | |
} | |
} | |
// [0, 1, 2, 3] - | |
// 4 | |
// array size 4 | |
// int[4] - 0 | |
// index = 0, | |
// found[index] = 1, found[2] = 1, > 4, | |
// scan minimum index with 0 -> size = 4 | |
// O(n) space, time complexity O(n) | |
// | |
// [1, 3, 2, 100] -> 0 | |
// size of 4 | |
// [3, 1, 2, 100] | |
// [100, 1, 2, 3] | |
// 100 -> outside 100 - | |
// 1 -> | |
// time complexity once - O(n) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment