README_EN.md

2288. Apply Discount to Prices

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Description

A sentence is a string of single-space separated words where each word can contain digits, lowercase letters, and the dollar sign '$'. A word represents a price if it is a sequence of digits preceded by a dollar sign.

• For example, "$100", "$23", and "$6" represent prices while "100", "$", and "$1e5" do not.

You are given a string sentence representing a sentence and an integer discount. For each word representing a price, apply a discount of discount% on the price and update the word in the sentence. All updated prices should be represented with exactly two decimal places.

Return a string representing the modified sentence.

Note that all prices will contain at most 10 digits.

 

Example 1:

Input: sentence = "there are $1 $2 and 5$ candies in the shop", discount = 50
Output: "there are $0.50 $1.00 and 5$ candies in the shop"
Explanation: 
The words which represent prices are "$1" and "$2". 
- A 50% discount on "$1" yields "$0.50", so "$1" is replaced by "$0.50".
- A 50% discount on "$2" yields "$1". Since we need to have exactly 2 decimal places after a price, we replace "$2" with "$1.00".

Example 2:

Input: sentence = "1 2 $3 4 $5 $6 7 8$ $9 $10$", discount = 100
Output: "1 2 $0.00 4 $0.00 $0.00 7 8$ $0.00 $10$"
Explanation: 
Applying a 100% discount on any price will result in 0.
The words representing prices are "$3", "$5", "$6", and "$9".
Each of them is replaced by "$0.00".

 

Constraints:

• 1 <= sentence.length <= 105
• sentence consists of lowercase English letters, digits, ' ', and '$'.
• sentence does not have leading or trailing spaces.
• All words in sentence are separated by a single space.
• All prices will be positive numbers without leading zeros.
• All prices will have at most 10 digits.
• 0 <= discount <= 100

Solutions

Python3

class Solution:
    def discountPrices(self, sentence: str, discount: int) -> str:
        ans = []
        for w in sentence.split():
            if w[0] == '$' and w[1:].isdigit():
                t = int(w[1:]) * (1 - discount / 100)
                ans.append('$' + '{:.2f}'.format(t))
            else:
                ans.append(w)
        return ' '.join(ans)

Java

class Solution {
    public String discountPrices(String sentence, int discount) {
        List<String> ans = new ArrayList<>();
        for (String w : sentence.split(" ")) {
            if (w.charAt(0) == '$' && isNumber(w.substring(1))) {
                double t = Long.parseLong(w.substring(1)) * (1 - discount / 100.0);
                ans.add("$" + String.format("%.2f", t));
            } else {
                ans.add(w);
            }
        }
        return String.join(" ", ans);
    }

    private boolean isNumber(String s) {
        if (s == null || "".equals(s)) {
            return false;
        }
        for (char c : s.toCharArray()) {
            if (!Character.isDigit(c)) {
                return false;
            }
        }
        return true;
    }
}

TypeScript

function discountPrices(sentence: string, discount: number): string {
    const sell = (100 - discount) / 100;
    let reg = new RegExp(/^(\$)(([1-9]\d*\.?\d*)|(0\.\d*))$/g);
    let arr = sentence.split(' ').map(d => {
        if (!reg.test(d)) return d;
        return d.replace(reg, (s, $1, $2) => {
            return `$${(sell * $2).toFixed(2)}`;
        });
    });
    return arr.join(' ');
}

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