Validate Date Function - Problem

Create a function that validates whether a given date is valid or not. The function should take three parameters: day, month, and year.

Your function must handle:

Leap years: A year is a leap year if it's divisible by 4, except for years divisible by 100 (unless also divisible by 400)
Month-specific day limits: Different months have different numbers of days (28/29, 30, or 31)
Invalid ranges: Month must be 1-12, day must be positive and within the month's limit

Return true if the date is valid, false otherwise.

Input & Output

Example 1 — Valid Leap Year Date

$ Input: day = 29, month = 2, year = 2024

› Output: true

💡 Note: 2024 is a leap year (divisible by 4), so February has 29 days. Day 29 is valid.

Example 2 — Invalid Non-Leap Year

$ Input: day = 29, month = 2, year = 2023

› Output: false

💡 Note: 2023 is not a leap year, so February only has 28 days. Day 29 is invalid.

Example 3 — Invalid Month

$ Input: day = 15, month = 13, year = 2024

› Output: false

💡 Note: Month 13 is invalid (must be 1-12), so the date is invalid regardless of day.

Constraints

1 ≤ day ≤ 31
1 ≤ month ≤ 12
1 ≤ year ≤ 9999

Visualization

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Asked in

G Google 25 a Amazon 18 M Microsoft 15

The key insight is understanding leap year rules (divisible by 4, except centuries need 400) and using array lookup for month-day limits. Best approach uses array lookup with helper function for clean, readable code. Time: O(1), Space: O(1)

Common Approaches

✓ Brute Force - Check Every Rule Separately

⏱️ Time: O(1) Space: O(1)

Check month range first, then determine days in month by checking each month individually, handle leap years with multiple conditions, finally validate day range.

Optimized - Array Lookup with Helper Function

⏱️ Time: O(1) Space: O(1)

Store days per month in an array for instant lookup, create a separate isLeapYear function with clean logic, then validate in a single streamlined flow.

Brute Force - Check Every Rule Separately — Algorithm Steps

Step 1: Check if month is between 1 and 12
Step 2: Use multiple if-else to get days in each month
Step 3: Check leap year with multiple conditions for February
Step 4: Check if day is between 1 and max days for that month

Visualization

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Step-by-Step Walkthrough

Month Check

Verify month is 1-12

Day Check

Check day is positive

Month Days

Determine max days for month

Final Validation

Compare day with max days

Code -

solution.c — C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

bool solution(int day, int month, int year) {
    // Check month range
    if (month < 1 || month > 12) {
        return false;
    }
    
    // Check day range
    if (day < 1) {
        return false;
    }
    
    // Determine days in month
    int maxDays;
    if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
        maxDays = 31;
    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
        maxDays = 30;
    } else { // February
        // Check leap year
        if (year % 4 != 0) {
            maxDays = 28;
        } else if (year % 100 != 0) {
            maxDays = 29;
        } else if (year % 400 != 0) {
            maxDays = 28;
        } else {
            maxDays = 29;
        }
    }
    
    return day <= maxDays;
}

int main() {
    int day, month, year;
    scanf("%d", &day);
    scanf("%d", &month);
    scanf("%d", &year);
    
    bool result = solution(day, month, year);
    printf(result ? "true\n" : "false\n");
    
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(1)

Fixed number of comparisons regardless of input

✓ Linear Growth

Space Complexity

O(1)

Only using a few variables for calculations

✓ Linear Space

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Validate Date Function - Problem

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Brute Force - Check Every Rule Separately — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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