g2201_2300.s2288_apply_discount_to_prices.Solution Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation
Java-based LeetCode algorithm problem solutions, regularly updated
There is a newer version: 1.38
package g2201_2300.s2288_apply_discount_to_prices;

// #Medium #String #2022_06_17_Time_82_ms_(97.98%)_Space_68.3_MB_(85.92%)

/**
 * 2288 - Apply Discount to Prices\.
 *
 * Medium
 *
 * 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`
**/
public class Solution {
    public String discountPrices(String sentence, int discount) {
        String[] words = sentence.split(" ");
        StringBuilder sb = new StringBuilder();
        for (String word : words) {
            sb.append(applyDiscount(word, discount));
            sb.append(" ");
        }
        sb.deleteCharAt(sb.length() - 1);
        return sb.toString();
    }

    private String applyDiscount(String s, int discount) {
        if (s.charAt(0) == '$' && s.length() > 1) {
            long price = 0;
            for (int i = 1; i < s.length(); i++) {
                if (!Character.isDigit(s.charAt(i))) {
                    // Error case. We could also use Long.parseLong() here.
                    return s;
                }
                price *= 10;
                price += (s.charAt(i) - '0') * (100 - discount);
            }
            String stringPrice = String.valueOf(price);
            if (price < 10) {
                return "$0.0" + stringPrice;
            }
            if (price < 100) {
                return "$0." + stringPrice;
            }
            return "$"
                    + stringPrice.substring(0, stringPrice.length() - 2)
                    + "."
                    + stringPrice.substring(stringPrice.length() - 2);
        }
        return s;
    }
}