247. Implement Basic Printf Formatter

Implement Basic Printf Formatter

Implement a basic version of printf in Java. Instead of printing to the console, the method must return the final formatted string.

The formatter supports three placeholders: %s for strings, %d for integers, and %f for floating point numbers. Placeholders must be replaced from left to right using the given argument values.

For %f, let x be the parsed floating point value. Compute rounded = round(x * 1,000,000) / 1,000,000, then print exactly 6 digits after the decimal point, padding trailing zeroes if needed. The decimal separator must be ..

Class

`BasicPrintfFormatter`

Method

Format

String format(String template, List<String> values)

Returns the final formatted string after replacing all supported placeholders in template.
%s is replaced by the next value exactly as given.
%d is replaced by the next value after parsing it as an integer.
%f is replaced by the next value after parsing it as a floating point number and formatting it with exactly 6 digits after the decimal point.
Placeholders are matched and replaced from left to right.
The input is valid: every placeholder is one of %s, %d, or %f, and the number of placeholders equals the number of values.

Constraints

1 ≤ template.length() ≤ 100,000
0 ≤ values.size() ≤ 10,000
1 ≤ values[i].length() ≤ 100
template contains only printable ASCII characters.
Every %d value represents a valid signed integer in the range -1,000,000,000 to 1,000,000,000.
Every %f value represents a valid signed decimal number in the range -1,000,000,000.0 to 1,000,000,000.0.
The result length will not exceed 1,000,000.
No parameter value will be null.

Examples

Example 1

format(template = "Hello %s, you have %d messages", values = List.of("Amit", "5"))

Output: "Hello Amit, you have 5 messages"

Explanation: %s is replaced by "Amit" and %d is replaced by integer 5.

Example 2

format(template = "Price: %f and item: %s", values = List.of("42.5", "book"))

Output: "Price: 42.500000 and item: book"

Explanation: %f is formatted with exactly 6 digits after the decimal point.

Example 3

format(template = "%s scored %d out of %d", values = List.of("Riya", "87", "100"))

Output: "Riya scored 87 out of 100"

Explanation: The placeholders are replaced in the same order as they appear in the template.