Decide Entry Using Logical Operators

A cinema lets someone in when they have a ticket and either are at least 18 or come with an adult. Given age, hasTicket and withAdult, return whether they may enter. Logical operators let one condition express a whole rule. The first solution spells the rule out with separate if checks; the second writes it as a single expression. Both rely on short-circuit evaluation: once the answer is known, the remaining checks are skipped.

Test Case 1:

Input:age = 15, hasTicket = true, withAdult = true

Output:true

Explanation:Under 18, but a ticket and an accompanying adult are enough.

Test Case 2:

Input:age = 30, hasTicket = false, withAdult = true

Output:false

Explanation:No ticket means no entry, whatever the age.

Constraints

◆0 ≤ age ≤ 120

Try the Dry Run

Mode

Approach

Approach & Solutions

Nested if StatementsGood

Check the rules one at a time and leave as soon as the answer is known. No ticket: return false straight away. Otherwise an adult (18 or older) may enter. Otherwise entry depends on whether an adult is with them.

TimeO(1)

SpaceO(1)

Java

Try it out

class Solution {
    public boolean canEnter(int age, boolean hasTicket, boolean withAdult) {
        if (!hasTicket) {
            return false;
        }
        if (age >= 18) {
            return true;
        }
        if (withAdult) {
            return true;
        }
        return false;
    }
}

One Logical ExpressionOptimal

Translate the rule straight into logic: a ticket AND (an adult OR accompanied by an adult). && / and and || / or combine the conditions, and the brackets make OR happen before AND. Both operators stop as soon as the answer is certain (short-circuit evaluation).