public:

bool isAdditiveNumber(string num) {

int n = num.length();

for (int i = 1; i <= n / 2; i++)

for (int j = 1; max(i, j) <= n - i - j; j++)

if (additive(i, j, num)) return true;

return false;

}

private:

bool additive(int i, int j, string& num) {

if (num[i] == '0' && j > 1) return false;

string a = num.substr(0, i);

string b = num.substr(i, j);

for (int k = i + j; k < num.length(); k += b.length()) {

b.swap(a);

b = add(a, b);

string tail = num.substr(k);

if (b.compare(tail.substr(0, b.size()))) return false;

}

return true;

}

string add(string& a, string& b) {

string s;

int i = a.size() - 1, j = b.size() - 1, c = 0;

while (i >= 0 || j >= 0) {

int d = (i >= 0 ? (a[i--] - '0') : 0) + (j >= 0 ? (b[j--] - '0') : 0) + c;

s += (d % 10 + '0');

c = d / 10;

}

if (c) s += ('0' + c);

reverse(s.begin(), s.end());

return s;

}

/* code */

Solution sol;

cout << sol.isAdditiveNumber("112358") << endl;

cout << sol.isAdditiveNumber("199100199") << endl;

return 0;

}