Leetcode_14

int queryCommonPrefix(char* s1,char* s2);char* longestCommonPrefix(char** strs, int strsSize) {    if(strsSize == 0)        return "";    if(strsSize == 1)        return strs[0];    int i = 1;    int longestLength = 0;    bool firstTime = true;    while(i < strsSize){        int longest = queryCommonPrefix(strs[0],strs[i]);        if(longestLength != 0 || firstTime){             if(firstTime){                 firstTime = false;                 longestLength = longest;             }             else{                 if(longestLength > longest){                     longestLength = longest;                 }             }          }        else{            break;        }        i++;    }    if(longestLength == 0)        return "";    char* returnStr = (char*)malloc(sizeof(char)*(longestLength+1));    for(i = 0;i < longestLength;i++){        returnStr[i] = strs[0][i];    }    returnStr[longestLength] = '\0';    return returnStr;}int queryCommonPrefix(char* s1,char* s2){    int length1 = strlen(s1);    int length2 = strlen(s2);    int i=0;    int j=0;    while(i< length1 && j < length2){        if(s1[i] == s2[j]){            i++;            j++;        }        else{            break;        }    }    return i;}