力扣-字符串-165 比较版本号

思路

使用两个指针遍历字符串，根据末尾或者.分割

代码

class Solution {int stringTonum(String str){if(str == "") return 0;int sum = 0, k = 1;for(int i = str.length() - 1; i >= 0; i--){sum += k * (str.charAt(i) - '0');k *= 10;}return sum;}public int compareVersion(String version1, String version2) {// v1 < v2 -1   int i = 0, j = 0;while(i < version1.length() || j < version2.length()){String str1="", str2="";for(; i < version1.length(); i++){if(version1.charAt(i) == '.'){i++;break;}else{str1 += version1.charAt(i);}}for(; j < version2.length(); j++){if(version2.charAt(j) == '.'){j++;break;}else{str2 += version2.charAt(j);}}if(stringTonum(str1) < stringTonum(str2)){return -1;}else if(stringTonum(str1) > stringTonum(str2)){return 1;}}return 0;}
}