2019, Republic, 11 day 2, numere solution added

2019/republic/11_d2/numere.cpp

@@ -0,0 +1,45 @@
+#include <iostream>
+using namespace std;
+
+int getMinIncrease(string num) {
+	int res = 0;
+	for (int i = 0; i < num.length(); i++) {
+		res += num[i] - '0';
+	}
+
+	res = res % 3;
+	return 3 - res;
+}
+
+
+int findPosToChange(string num, int INC) {
+	for (int i = 0; i < num.length(); i++) {
+		if (num[i] != '9' && num[i] + INC <= '9') {
+			return i;
+		}
+	}
+	return num.length() - 1;
+}
+
+
+int main() {
+	string num;
+	cin >> num;
+
+	const int INC = getMinIncrease(num);
+	const int POS = findPosToChange(num, INC);
+
+	// cout << INC << " " << POS << endl;
+	if (num[POS] + INC <= '9') {
+		int extra_space = (9 - (num[POS] - '0') - INC);
+		num[POS] = num[POS] + INC + extra_space - (extra_space % 3);
+	} else if (3 - INC != 0) {
+		num[POS] -= 3 - INC;
+	} else {
+		num[POS] -= 3;
+	}
+
+	cout << num << endl;
+
+	return 0;
+}