問題：A - ABD #include <iostream> using namespace std; int main(void){ int n; cin.tie(0); ios::sync_with_stdio(false); cin >> n; cout << (n <= 999? "ABC" : "ABD") << "\n"; return 0; }</iostream>

問題：B - Cut and Count #include <iostream> #include <string> using namespace std; #define REP(i,n) for (int i = 0; i < (n); ++i) #define FOR(i, a, b) for (int i = (a); i < (b); ++i) bool isMatch(string str, int s, int g, char c) { FOR(i, s, g) { if (str[i]</string></iostream>…