README_EN.md

05.02. Bianry Number to String

中文文档

Description

Given a real number between O and 1 (e.g., 0.72) that is passed in as a double, print the binary representation. If the number cannot be represented accurately in binary with at most 32 characters, print "ERROR".

Example1:

 Input: 0.625
 Output: "0.101"

Example2:

 Input: 0.1
 Output: "ERROR"
 Note: 0.1 cannot be represented accurately in binary.

Note:

1. This two charaters "0." should be counted into 32 characters.

Solutions

Python3

class Solution:
    def printBin(self, num: float) -> str:
        ans = '0.'
        while len(ans) < 32 and num:
            num *= 2
            x = int(num)
            ans += str(x)
            num -= x
        return 'ERROR' if num else ans

Java

class Solution {
    public String printBin(double num) {
        StringBuilder ans = new StringBuilder("0.");
        while (ans.length() < 32 && num != 0) {
            num *= 2;
            int x = (int) num;
            ans.append(x);
            num -= x;
        }
        return num != 0 ? "ERROR" : ans.toString();
    }
}

C++

class Solution {
public:
    string printBin(double num) {
        string ans = "0.";
        while (ans.size() < 32 && num != 0) {
            num *= 2;
            int x = (int) num;
            ans.push_back('0' + x);
            num -= x;
        }
        return num != 0 ? "ERROR" : ans;
    }
};

Go

func printBin(num float64) string {
	ans := &strings.Builder{}
	ans.WriteString("0.")
	for ans.Len() < 32 && num != 0 {
		num *= 2
		x := byte(num)
		ans.WriteByte('0' + x)
		num -= float64(x)
	}
	if num != 0 {
		return "ERROR"
	}
	return ans.String()
}

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