LeetCode Compare Version Numbers

class Solution {

public:

    int compareVersion(string version1, string version2) {

        vector<int> v1 = getVersionParts(version1);

        vector<int> v2 = getVersionParts(version2);



        int i = 0, j = 0;

        int len1 = v1.size();

        int len2 = v2.size();





        while (i < len1 && j < len2) {

            if (v1[i] < v2[i]) {

                return -1;

            } else if (v1[i] > v2[i]) {

                return 1;

            }

            i++, j++;

        }

        int r = 0;

        while (i < len1) {

            r += v1[i++];

        }

        if (r != 0) {

            return 1;

        }

        r = 0;

        while (j < len2) {

            r += v2[j++];

        }

        if (r != 0) {

            return -1;

        }

        return 0;

    }



    vector<int> getVersionParts(string& version) {

        vector<int> parts;

        int len = version.length();

        int v = 0;

        char d = '\0';

        for (int i=0; i<len; i++) {

            d = version[i];

            if (d == '.') {

                parts.push_back(v);

                v = 0;

                continue;

            }



            v = v * 10 + d - '0';

        }

        if (d != '.') {

            parts.push_back(v);

        }

        return parts;

    }

};

水一发，改进一下贴一个简化版的：

class Solution {

public:

    int compareVersion(string version1, string version2) {

        int part1 = 0;

        int part2 = 0;

        int len1 = version1.length();

        int len2 = version2.length();

        

        int i = 0, j = 0;

        while (i < len1 || j < len2) {

            char ch;

            while (i < len1 && (ch = version1[i++]) != '.') {

                part1 += ch - '0' + part1 * 10;

            }



            while(j < len2 && (ch = version2[j++]) != '.') {

                part2 += ch - '0' + part2 * 10;

            }

            if (part1 > part2) {

                return 1;

            } else if (part1 < part2) {

                return -1;

            } else {

                // part equal, continue to compare next version part

            }

            part1 = part2 = 0;

        }

        

        return 0;

    }

};

 看来功力下降了，这题都做的好烦，有写了个超繁，还是第二个比较好：

 

class Solution {

public:

    int compareVersion(string version1, string version2) {

        int len1 = version1.size();

        int len2 = version2.size();

        

        int val1 = 0;

        int val2 = 0;

        

        int p1 = 0;

        int p2 = 0;

        char ch = 0;

        while (p1 < len1 || p2 < len2) {

            while (p1 < len1 && (ch = version1[p1++]) != '.') {

                val1 = val1 * 10 + ch - '0';

            }

            

            while (p2 < len2 && (ch = version2[p2++]) != '.') {

                val2 = val2 * 10 + ch - '0';

            }

            if (val1 > val2) {

                return 1;

            } else if (val2 > val1) {

                return -1;

            }

            val1 = val2 = 0;

        }

        

        return 0;

    }

};