题目：
题解：
class Solution {
public:string validIPAddress(string queryIP) {if (queryIP.find('.') != string::npos) {// IPv4int last = -1;for (int i = 0; i < 4; ++i) {int cur = (i == 3 ? queryIP.size() : queryIP.find('.', last + 1));if (cur == string::npos) {return "Neither";}if (cur - last - 1 < 1 || cur - last - 1 > 3) {return "Neither";}int addr = 0;for (int j = last + 1; j < cur; ++j) {if (!isdigit(queryIP[j])) {return "Neither";}addr = addr * 10 + (queryIP[j] - '0');}if (addr > 255) {return "Neither";}if (addr > 0 && queryIP[last + 1] == '0') {return "Neither";}if (addr == 0 && cur - last - 1 > 1) {return "Neither";}last = cur;}return "IPv4";}else {// IPv6int last = -1;for (int i = 0; i < 8; ++i) {int cur = (i == 7 ? queryIP.size() : queryIP.find(':', last + 1));if (cur == string::npos) {return "Neither";}if (cur - last - 1 < 1 || cur - last - 1 > 4) {return "Neither";}for (int j = last + 1; j < cur; ++j) {if (!isdigit(queryIP[j]) && !('a' <= tolower(queryIP[j]) && tolower(queryIP[j]) <= 'f')) {return "Neither";}}last = cur;}return "IPv6";}}
};