A - Count Takahashi 解説 by en_translator
For beginners
- If you are new to learning programming and do not know where to start, please try Problem A "Welcome to AtCoder" from practice contest. There you can find a sample code for each language.
- Also, if you are not familiar with problems in programming contests, we recommend you to try some problems in "AtCoder Beginners Selection".
- 「C++入門 AtCoder Programming Guide for beginners (APG4b)」 is a C++ tutorial for competitive programmers. Sadly, this is only in Japanese too.
1. A naive solution
This problem can be solved by coding the following procedure.
- Define an integer variable \(\operatorname{ans}\) for the integer, initializing it with \(0\).
- Receive \(N\) from the standard input.
- Repeat the following operation \(N\) times.
- Receive a string from the standard input.
- If the received string equals
Takahashi
, add \(1\) to \(\operatorname{ans}\).
- Print the value \(\operatorname{ans}\).
With a loop with a for
statement and conditional branches with if statements, this can be correctly coded.
The following is sample code.
Sample code in C++
#include <iostream>
using namespace std;
int main() {
// Counter for the number of occurrences of Takahashi
int ans = 0;
int N;
cin >> N;
for (int i = 0; i < N; i++) {
string S;
cin >> S;
// If S equals Takahashi, increment the counter
if (S == "Takahashi") {
ans++;
}
}
// Print the value of the counter
cout << ans << endl;
return 0;
}
Python での実装例
# Counter for the number of occurrences of Takahashi
ans = 0
N = int(input())
for _ in range(N):
S = input()
# If S equals Takahashi, increment the counter
if S == 'Takahashi':
ans += 1
# Print the value of the counter
print(ans)
2. A little tricky solution
The answer to this problem equals the number of occurrences of T
in the input, or the number of occurrences of occurrences of s
in the input.
If your language allows you to receive the input at once, or to count the occurrences of a specific character in a string easily, then using this approach may reduce the implementation.
Sample code in Haskell
main = interact $ show . length . filter ('T' ==)
Sample code in Python
print(open(0).read().count('T'))
Sample code in Bash
grep T | wc -l
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