Overview

Given temperature data for \(N\) days, the problem asks you to count how many days have a temperature of at least \(L\) and at most \(R\).

Analysis

This problem is very straightforward — you simply need to check each day’s temperature one by one to see if it falls within the specified range.

For example, consider the case where \(N = 5\), \(L = 15\), \(R = 25\), and the temperatures are \([10, 18, 25, 30, 20]\).

In this case, the answer is 3 days.

No special algorithm is needed — a single loop over the \(N\) days is sufficient. Since \(N\) is at most \(10^5\), checking each day one by one runs fast enough.

Algorithm

1. Read \(N\), \(L\), \(R\) from the input.
2. Initialize a counter count to \(0\).
3. Repeat \(N\) times, reading the temperature \(T_i\) each time.
4. If \(L \leq T_i \leq R\), increment count by \(1\).
5. Finally, output count.

In Python, you can write L <= T <= R to check “\(T\) is at least \(L\) and at most \(R\)” in one expression. This is equivalent to L <= T and T <= R.

Complexity

• Time complexity: \(O(N)\) — we simply check each day’s temperature once
• Space complexity: \(O(1)\) — only a single counter is needed; there is no need to store the temperatures

Implementation Notes

• In Python, you can use chained comparisons like if L <= T <= R:, which allows you to write the condition concisely.

• The temperature \(T_i\) or the lower bound \(L\) may be negative, but comparison operations handle this correctly as-is, so no special treatment is needed.

• There is no need to store all temperatures in a list — reading and checking one day at a time saves memory.

  Source Code

N, L, R = map(int, input().split())
count = 0
for _ in range(N):
    T = int(input())
    if L <= T <= R:
        count += 1
print(count)

This editorial was generated by claude4.6opus-thinking.