SEVENRINGS - Editorial

editorial
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PROBLEM LINK:

Practice
Contest: Division 1
Contest: Division 2
Contest: Division 3
Contest: Division 4

Author: notsoloud
Tester & Editorialist: iceknight1093

DIFFICULTY:

568

PREREQUISITES:

None

PROBLEM:

Chef purchased N items, each with a cost of X.
A valid phone number is a 5-digit number that has no leading zeros.

Is Chef’s total spending equivalent to a valid phone number?

EXPLANATION:

Buying N items for X each, Chef spent N\cdot X in total; so all that needs to be done is to check whether N\cdot X is a 5-digit number.

This can be done is various ways, for example:

  • Convert N\cdot X to a string and check if its length equals 5.
    For example, you can use std::to_string in C++ or str in Python; or
  • Use a while loop to count the number of digits in N\cdot X, and check if it equals 5; or
  • Check if 10000 \leq X \leq 99999.

TIME COMPLEXITY

\mathcal{O}(1) per testcase.

CODE:

Editorialist's code (Python) 
for _ in range(int(input())):
    n, x = map(int, input().split())
    tot = n*x
    print('Yes' if len(str(tot)) == 5 else 'No')