問題：A - 9x9 #include <iostream> using namespace std; int main(void) { int a, b; cin.tie(0); ios::sync_with_stdio(false); cin >> a >> b; if (9 < a || 9 < b) { cout << -1 << "\n"; } else { cout << a * b << "\n"; } return 0; }</iostream>

問題：B - TAKOYAKI FESTIVAL 2019 #include <iostream> #include <vector> 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) int main(void) { int n, sum = 0; cin.tie(0); ios::sync_with_stdi</vector></iostream>…

問題：A - Curtain #include <algorithm> #include <iostream> using namespace std; int main(void) { int a, b; cin.tie(0); ios::sync_with_stdio(false); cin >> a >> b; cout << max(0, a - 2 * b) << "\n"; return 0; }</iostream></algorithm>

問題：B - Roller Coaster #include <iostream> using namespace std; #define REP(i, n) for (int i = 0; i < (n); ++i) int main(void) { int n, k, h, ans = 0; cin.tie(0); ios::sync_with_stdio(false); cin >> n >> k; REP(i, n) { cin >> h; if (k <= h) { ans+</iostream>…

問題：A - Odds of Oddness #include <iomanip> #include <iostream> using namespace std; int main(void) { int n; cin.tie(0); ios::sync_with_stdio(false); cin >> n; cout << fixed << setprecision(10) << (n % 2 == 0? n / 2 / (double) n : (n + 1) / 2 / (double) n) <</iostream></iomanip>…