# Apply Discount to Prices

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 integers without leading zeros.
• All prices will have at most `10` digits.
• `0 <= discount <= 100`

SOLUTION:

``````class Solution:
def discountPrices(self, sentence: str, discount: int) -> str:
words = sentence.split()
n = len(words)
for i in range(n):
if words[i] == '\$' and words[i][1:].isnumeric():
val = words[i][1:]
newprice = eval(f"{val} * (1 - {discount} / 100)")
newprice = "{:.2f}".format(newprice)
words[i] = f"\${newprice}"
return " ".join(words)
``````