T1：First ABC
模拟
代码实现
n = int(input())
s = input()
A = B = C = False
for i in range(n):
if s[i] == 'A': A = True
if s[i] == 'B': B = True
if s[i] == 'C': C = True
if A and B and C:
exit(print(i+1))
T2：Vacation Together
暴力
代码实现
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
int main() {
int n, d;
cin >> n >> d;
vector<string> s(n);
rep(i, n) cin >> s[i];
string t;
rep(i, d) {
bool ok = true;
rep(j, n) if (s[j][i] == 'x') ok = false;
if (ok) t += 'o'; else t += 'x';
}
int ans = 0, now = 0;
rep(i, d) {
if (t[i] == 'o') now++; else now = 0;
ans = max(ans, now);
}
cout << ans << '\n';
return 0;
}
T3：Find it!
注意到无论从哪个点开始搜，最终都会走到环里，所以当第一次走到已经走过的点时可以再走一圈
代码实现
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
int main() {
int n;
cin >> n;
vector<int> a(n+1);
rep(i, n) cin >> a[i+1];
vector<int> id(n+1);
int k = 1;
int v = 1;
while (id[v] == 0) {
id[v] = k; k++;
v = a[v];
}
vector<int> ans;
int len = k-id[v];
rep(i, len) {
ans.push_back(v);
v = a[v];
}
cout << len << '\n';
for (int v : ans) cout << v << ' ';
return 0;
}