golang實現lintcode部分算法

1.https://www.lintcode.com/problem/digit-counts/description

Description

中文English

Count the number of k's between 0 and n. k can be 0 - 9.

Example

Input:
k = 1, n = 12
Output:
5
Explanation:
In [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], we found that one appeared five times (1, 10, 11, 12)(Note that there are two 1 in 11).

Code

/**
Input:
k = 1, n = 1
Output:
1
Explanation:
In [0, 1], we found that 1 appeared once (1).
*/
func CountNumber(k int ,n int) int  {
	count := 0
	var kStr = strconv.Itoa(k)
	for i :=0 ; i <= n ; i++ {
		tempStr := strconv.Itoa(i)
		if tempStr == kStr && len(tempStr) == 1{
			count ++
		}else {
			for j :=0 ; j < len(tempStr); j++ {
				if kStr == string(tempStr[j]){
					count ++
				}
			}
		}
	}
	return count
}

測試：

package main

import (
	"fmt"
	"src/lintcode"
)

func main()  {
	// 測試出現頻率
	k := 1
	n := 12
	fmt.Println("輸入",k,n)
	number := lintcode.CountNumber(k, n)
	fmt.Println("輸出",number)
}

輸出：

2. https://www.lintcode.com/problem/ugly-number-ii/description

Description

Ugly number is a number that only have prime factors 2, 3 and 5.

Design an algorithm to find the nth ugly number. The first 10 ugly numbers are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12...

// 尋找醜陋數

/**
尋找醜陋數
 */
func FindUgly(endFlag int) int  {
	if endFlag < 1 {
		return -1
	}
	target := 1
	flag := 1
	for {
		temp := target
		for ;target % 2 == 0;  {
			target = target / 2
		}
		for ;target % 3 == 0;  {
			target = target / 3
		}
		for ;target % 5 == 0;  {
			target = target / 5
		}
		if flag >= endFlag && target == 1{
			return temp
		}

		if target == 1{
			flag ++
		}
		target = temp + 1
	}
}

func main()  {
	// 測試醜數
	input := 9
	output := lintcode.FindUgly(input)
	fmt.Println(input, output)
}

輸出：

 

3. https://www.lintcode.com/problem/kth-largest-element/description

Description

中文English

在數組中找到第 k 大的元素。

你可以交換數組中的元素的位置

Example

樣例 1：

輸入：
n = 1, nums = [1,3,4,2]
輸出：
4

樣例 2：

輸入：
n = 3, nums = [9,3,2,4,8]
輸出：
4

Challenge

要求時間複雜度爲O(n)，空間複雜度爲O(1)。

// 代碼

 

 

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