GuoXin Li's Blog

LeetCode504. Base 7

LeetCode
字数统计: 199阅读时长: 1 min
2020/02/29 Share

504. Base 7

504. Base 7

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: “202”
Example 2:

Input: -7
Output: “-10”
Note: The input will be in range of [-1e7, 1e7].

Resolution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
class Solution {
    public String convertToBase7(int num) {
        StringBuilder com = new StringBuilder();
        if(num == 0) return "0";
        boolean flag = num < 0;
        num = Math.abs(num);
        while(num != 0){
            com.append(num % 7);
            num = num/7;
        }
        StringBuilder com_ = com.reverse();
        String str = com_.toString();
        return flag ? "-"+str : str;
    }
}

Time Complexity: O(logn)

Space Complexity: O(logn)

note:

important: num.toString( ); ——> wrong. Object numberdo not has the method “toString( )”

don’t foget to check the initial condition firstly.

A good solution of java Integer

1
2
3
public String convertToBase7(int num) {
    return Integer.toString(num, 7);
}

C++ solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
class Solution {
public:
    string convertToBase7(int num) {
        string ans;
        bool is_nagetive = num < 0;
        num = abs(num);
        do{
            ans = std::to_string(num%7) + ans;
            num /=7;
        }while(num > 0);
        if(is_nagetive){
            return "-"+ans;
        }
        return ans;
    }
};

key:implicit handle of special case 0 —>> using do{ }while( );

Time Complexity: O(logn)

Space Complexity: O(logn)

CATALOG
  1. 1. 504. Base 7
  2. 2. Example 1:
  3. 3. Resolution
  4. 4. A good solution of java Integer
  5. 5. C++ solution
Total : 89
2022
2021
2020
2019
2018
essay Deep Learning Paper-reading learning-note C++ CUDA cmake LeetCode DataStructure Numpy OS-Linux PAT slidingwindow git golang BuaaAssignments CG
Machine-Learning Data-Structure