Defanging an IP Address Problem & Solution

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")

static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class Solution {
public:
  string defangIPaddr(string address) {
    string dot = ".";

    int i = 0, j;
    while ((j = address.find(dot, i)) != string::npos) {
      address.replace(j, dot.size(), "[.]");
      i = j + 3;
    }

    return address;
  }
};