不太友好的一场。
题目链接：https://codeforces.com/contest/1214
A：
想了很久优美做法，发现还不如直接一发暴力正确。
1 /* basic header */
2 #include <bits/stdc++.h>
3 /* define */
4 #define ll long long
5 #define dou double
6 #define pb emplace_back
7 #define mp make_pair
8 #define sot(a,b) sort(a+1,a+1+b)
9 #define rep1(i,a,b) for(int i=a;i<=b;++i)
10 #define rep0(i,a,b) for(int i=a;i<b;++i)
11 #define eps 1e-8
12 #define int_inf 0x3f3f3f3f
13 #define ll_inf 0x7f7f7f7f7f7f7f7f
14 #define lson (curpos<<1)
15 #define rson (curpos<<1|1)
16 /* namespace */
17 using namespace std;
18 /* header end */
19
20 int n, d, e;
21
22 int main() {
23 scanf("%d%d%d", &n, &d, &e);
24 int dollarUnit = d, euroUnit = e * 5, ans = n;
25 for (int numOfDollar = 0; numOfDollar <= n / dollarUnit; numOfDollar++) {
26 int remainRubles = n - numOfDollar * dollarUnit;
27 remainRubles -= remainRubles / euroUnit * euroUnit;
28 ans = min(ans, remainRubles);
29 }
30 for (int numOfEuro = 0; numOfEuro <= n / euroUnit; numOfEuro += 5) {
31 int remainRubles = n - numOfEuro * euroUnit;
32 remainRubles -= remainRubles / dollarUnit * dollarUnit;
33 ans = min(ans, remainRubles);
34 }
35 printf("%d\n", ans);
36 return 0;
37 }
B：
比A简单多了的傻题。
1 /* basic header */
2 #include <bits/stdc++.h>
3 /* define */
4 #define ll long long
5 #define dou double
6 #define pb emplace_back
7 #define mp make_pair
8 #define sot(a,b) sort(a+1,a+1+b)
9 #define rep1(i,a,b) for(int i=a;i<=b;++i)
10 #define rep0(i,a,b) for(int i=a;i<b;++i)
11 #define eps 1e-8
12 #define int_inf 0x3f3f3f3f
13 #define ll_inf 0x7f7f7f7f7f7f7f7f
14 #define lson (curpos<<1)
15 #define rson (curpos<<1|1)
16 /* namespace */
17 using namespace std;
18 /* header end */
19
20 int b, g, n;
21
22 int main() {
23 scanf("%d%d%d", &b, &g, &n);
24 ll ans = 0;
25 for (int i = 0; i <= b; i++)
26 if (n - i >= 0 && n - i <= g) ans++;
27 printf("%lld\n", ans);
28 return 0;
29 }
C：
check一次看看是否合法即可。
1 /* basic header */
2 #include <bits/stdc++.h>
3 /* define */
4 #define ll long long
5 #define dou double
6 #define pb emplace_back
7 #define mp make_pair
8 #define sot(a,b) sort(a+1,a+1+b)
9 #define rep1(i,a,b) for(int i=a;i<=b;++i)
10 #define rep0(i,a,b) for(int i=a;i<b;++i)
11 #define eps 1e-8
12 #define int_inf 0x3f3f3f3f
13 #define ll_inf 0x7f7f7f7f7f7f7f7f
14 #define lson (curpos<<1)
15 #define rson (curpos<<1|1)
16 /* namespace */
17 using namespace std;
18 /* header end */
19
20 const int maxn = 2e5 + 10;
21 int n;
22 char s[maxn];
23
24 int main() {
25 scanf("%d", &n);
26 scanf("%s", s + 1);
27 if (n & 1) return puts("No"), 0;
28 stack<int>st;
29 while (!st.empty()) st.pop();
30 for (int i = 1; i <= n; i++) {
31 if (s[i] == '(') st.push(0);
32 if (s[i] == ')') {
33 if (!st.empty() && st.top() == 0) st.pop();
34 else st.push(1);
35 }
36 }
37 if (st.empty()) return puts("Yes"), 0;
38 else {
39 if ((int)st.size() != 2) return puts("No"), 0;
40 int tmp1 = st.top(), tmp2;
41 st.pop();
42 tmp2 = st.top();
43 if (tmp1 != tmp2) return puts("Yes"), 0;
44 else return puts("No"), 0;
45 }
46 return 0;
47 }