g1901_2000.s1903_largest_odd_number_in_string.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1901_2000.s1903_largest_odd_number_in_string;

// #Easy #String #Math #Greedy #2022_05_11_Time_6_ms_(23.18%)_Space_43.2_MB_(81.76%)

/**
 * 1903 - Largest Odd Number in String\.
 *
 * Easy
 *
 * You are given a string `num`, representing a large integer. Return _the **largest-valued odd** integer (as a string) that is a **non-empty substring** of_ `num`_, or an empty string_ `""` _if no odd integer exists_.
 *
 * A **substring** is a contiguous sequence of characters within a string.
 *
 * **Example 1:**
 *
 * **Input:** num = "52"
 *
 * **Output:** "5"
 *
 * **Explanation:** The only non-empty substrings are "5", "2", and "52". "5" is the only odd number.
 *
 * **Example 2:**
 *
 * **Input:** num = "4206"
 *
 * **Output:** ""
 *
 * **Explanation:** There are no odd numbers in "4206".
 *
 * **Example 3:**
 *
 * **Input:** num = "35427"
 *
 * **Output:** "35427"
 *
 * **Explanation:** "35427" is already an odd number.
 *
 * **Constraints:**
 *
 * *   1 <= num.length <= 10⁵
 * *   `num` only consists of digits and does not contain any leading zeros.
**/
public class Solution {
    public String largestOddNumber(String num) {
        for (int i = num.length() - 1; i >= 0; i--) {
            if (Integer.parseInt("" + num.charAt(i)) % 2 == 1) {
                return num.substring(0, i + 1);
            }
        }
        return "";
    }
}