题解 | #合法IP#
合法IP
https://www.nowcoder.com/practice/995b8a548827494699dc38c3e2a54ee9
#include <cctype>
#include <iostream>
#include <vector>
using namespace std;
bool isIp(string ip) {
int left = 0, right = 0;
int n = ip.size();
vector<int> nums(4);
while (right < n) {
for (int i = 0; i < 4; ++i) {
left = right;
if (!isdigit(ip[right])) return false;
while (isdigit(ip[right])) right++;
string temp = ip.substr(left, right - left);
if (temp[0] == '0' && temp.size() > 1) return false;
nums[i] = stoi(temp);
if (nums[i] < 0 || nums[i] > 255) return false;
if (i < 3) {
if (right < n && ip[right++] != '.') return false;
}
}
}
if (right != n) return false;
return true;
}
int main() {
string ip;
while (cin >> ip) {
if (isIp(ip)) {
cout << "YES" << endl;
} else {
cout << "NO" << endl;
}
}
}
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