Overflow in intermediate arithmetic
Wrong move: Temporary multiplications exceed integer bounds.
Usually fails on: Large inputs wrap around unexpectedly.
Fix: Use wider types, modular arithmetic, or rearranged operations.
Build confidence with an intuition-first walkthrough focused on math fundamentals.
You are given coordinates, a string that represents the coordinates of a square of the chessboard. Below is a chessboard for your reference.
Return true if the square is white, and false if the square is black.
The coordinate will always represent a valid chessboard square. The coordinate will always have the letter first, and the number second.
Example 1:
Input: coordinates = "a1" Output: false Explanation: From the chessboard above, the square with coordinates "a1" is black, so return false.
Example 2:
Input: coordinates = "h3" Output: true Explanation: From the chessboard above, the square with coordinates "h3" is white, so return true.
Example 3:
Input: coordinates = "c7" Output: false
Constraints:
coordinates.length == 2'a' <= coordinates[0] <= 'h''1' <= coordinates[1] <= '8'Problem summary: You are given coordinates, a string that represents the coordinates of a square of the chessboard. Below is a chessboard for your reference. Return true if the square is white, and false if the square is black. The coordinate will always represent a valid chessboard square. The coordinate will always have the letter first, and the number second.
Start with the most direct exhaustive search. That gives a correctness anchor before optimizing.
Pattern signal: Math
"a1"
"h3"
"c7"
check-if-two-chessboard-squares-have-the-same-color)Source-backed implementations are provided below for direct study and interview prep.
// Accepted solution for LeetCode #1812: Determine Color of a Chessboard Square
class Solution {
public boolean squareIsWhite(String coordinates) {
return (coordinates.charAt(0) + coordinates.charAt(1)) % 2 == 1;
}
}
// Accepted solution for LeetCode #1812: Determine Color of a Chessboard Square
func squareIsWhite(coordinates string) bool {
return (coordinates[0]+coordinates[1])%2 == 1
}
# Accepted solution for LeetCode #1812: Determine Color of a Chessboard Square
class Solution:
def squareIsWhite(self, coordinates: str) -> bool:
return (ord(coordinates[0]) + ord(coordinates[1])) % 2 == 1
// Accepted solution for LeetCode #1812: Determine Color of a Chessboard Square
impl Solution {
pub fn square_is_white(coordinates: String) -> bool {
let s = coordinates.as_bytes();
((s[0] + s[1]) & 1) == 1
}
}
// Accepted solution for LeetCode #1812: Determine Color of a Chessboard Square
function squareIsWhite(coordinates: string): boolean {
return ((coordinates.charCodeAt(0) + coordinates.charCodeAt(1)) & 1) === 1;
}
Use this to step through a reusable interview workflow for this problem.
Simulate the process step by step — multiply n times, check each number up to n, or iterate through all possibilities. Each step is O(1), but doing it n times gives O(n). No extra space needed since we just track running state.
Math problems often have a closed-form or O(log n) solution hidden behind an O(n) simulation. Modular arithmetic, fast exponentiation (repeated squaring), GCD (Euclidean algorithm), and number theory properties can dramatically reduce complexity.
Review these before coding to avoid predictable interview regressions.
Wrong move: Temporary multiplications exceed integer bounds.
Usually fails on: Large inputs wrap around unexpectedly.
Fix: Use wider types, modular arithmetic, or rearranged operations.