# 2288. Apply Discount to Prices

## 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

• class Solution {
public String discountPrices(String sentence, int discount) {
String[] words = sentence.split(" ");
for (int i = 0; i < words.length; ++i) {
if (check(words[i])) {
double t = Long.parseLong(words[i].substring(1)) * (1 - discount / 100.0);
words[i] = String.format("$%.2f", t); } } return String.join(" ", words); } private boolean check(String s) { if (s.charAt(0) != '$' || s.length() == 1) {
return false;
}
for (int i = 1; i < s.length(); ++i) {
if (!Character.isDigit(s.charAt(i))) {
return false;
}
}
return true;
}
}

• class Solution {
public:
string discountPrices(string sentence, int discount) {
istringstream is(sentence);
string w;
string ans;
auto check = [](string s) {
if (s[0] != '$' || s.size() == 1) { return false; } for (int i = 1; i < s.size(); ++i) { if (!isdigit(s[i])) { return false; } } return true; }; while (is >> w) { if (check(w)) { long long v = stoll(w.substr(1)) * (100 - discount); char t[20]; sprintf(t, "$%lld.%02lld", v / 100, v % 100);
ans += t;
} else {
ans += w;
}
ans += ' ';
}
ans.pop_back();
return ans;
}
};

• class Solution:
def discountPrices(self, sentence: str, discount: int) -> str:
ans = []
for w in sentence.split():
if w[0] == '$' and w[1:].isdigit(): w = f'${int(w[1:]) * (1 - discount / 100):.2f}'
ans.append(w)
return ' '.join(ans)


• func discountPrices(sentence string, discount int) string {
words := strings.Split(sentence, " ")
for i, w := range words {
if w[0] == '$' { if v, err := strconv.Atoi(w[1:]); err == nil { words[i] = fmt.Sprintf("$%.2f", float64(v*(100-discount))/100)
}
}
}
return strings.Join(words, " ")
}

• 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(' ');
}