LeetCode/src/medium/CompareVersionNumbers.java at master · chenyiAlone/LeetCode · GitHub

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package medium;
/**
 * ClassName: CompareVersionNumbers.java
 * Auther: chenyiAlone
 * Create Time: 2019/5/2 20:33
 * Description: No.165
 * 思路:
 *      1. java 正则表达式分割 "[.]"
 *      2. 遍历得到的 strs
 *      3. 数值大的那个即为更后的版本
 *
 *
 * Compare two version numbers version1 and version2.
 * If version1 > version2 return 1; if version1 < version2 return -1;otherwise return 0.
 *
 * You may assume that the version strings are non-empty and contain only digits and the . character.
 *
 * The . character does not represent a decimal point and is used to separate number sequences.
 *
 * For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.
 *
 * You may assume the default revision number for each level of a version number to be 0. For example, version number 3.4 has a revision number of 3 and 4 for its first and second level revision number. Its third and fourth level revision number are both 0.
 *
 *
 *
 * Example 1:
 *
 * Input: version1 = "0.1", version2 = "1.1"
 * Output: -1
 * Example 2:
 *
 * Input: version1 = "1.0.1", version2 = "1"
 * Output: 1
 * Example 3:
 *
 * Input: version1 = "7.5.2.4", version2 = "7.5.3"
 * Output: -1
 * Example 4:
 *
 * Input: version1 = "1.01", version2 = "1.001"
 * Output: 0
 * Explanation: Ignoring leading zeroes, both “01” and “001" represent the same number “1”
 * Example 5:
 *
 * Input: version1 = "1.0", version2 = "1.0.0"
 * Output: 0
 * Explanation: The first version number does not have a third level revision number, which means its third level revision number is default to "0"
 *
 *
 * Note:
 *
 * Version strings are composed of numeric strings separated by dots . and this numeric strings may have leading zeroes.
 * Version strings do not start or end with dots, and they will not be two consecutive dots.
 *
 *
 */
public class CompareVersionNumbers {
    public int compareVersion(String version1, String version2) {
        String[] strs1 = version1.split("[.]");
        String[] strs2 = version2.split("[.]");

        return cmp(strs1, strs2);
    }

    private int cmp(String[] strs1, String[] strs2) {
        int len1 = strs1.length;
        int len2 = strs2.length;
        System.out.println("len1 = " + len1 + ", len2 = " + len2);
        int i = 0;
        while (i < len1 || i < len2) {
            if (i >= len1) {
                if (Integer.valueOf(strs2[i]) > 0)
                    return -1;
            } else if (i >= len2) {
                if (Integer.valueOf(strs1[i]) > 0) {
                    return 1;
                }
            } else {
                int v1 = Integer.valueOf(strs1[i]);
                int v2 = Integer.valueOf(strs2[i]);
                if (v1 != v2)
                    return v1 > v2 ? 1 : -1;
            }
            i++;
        }
        return 0;
    }
}