StrobogrammaticNumber.java

packagecom.thealgorithms.maths;

importjava.util.HashMap;
importjava.util.Map;

/**
 * A strobogrammatic number is a number that remains the same when rotated 180 degrees.
 * In other words, the number looks the same when rotated upside down.
 * Examples of strobogrammatic numbers are "69", "88", "818", and "101".
 * Numbers like "609" or "120" are not strobogrammatic because they do not look the same when rotated.
 */
publicclassStrobogrammaticNumber {
/**
 * Check if a number is strobogrammatic
 * @param number the number to be checked
 * @return true if the number is strobogrammatic, false otherwise
 */
publicbooleanisStrobogrammatic(Stringnumber) {
Map<Character, Character> strobogrammaticMap = newHashMap<>();
strobogrammaticMap.put('0', '0');
strobogrammaticMap.put('1', '1');
strobogrammaticMap.put('6', '9');
strobogrammaticMap.put('8', '8');
strobogrammaticMap.put('9', '6');

intleft = 0;
intright = number.length() - 1;

while (left <= right) {
charleftChar = number.charAt(left);
charrightChar = number.charAt(right);

if (!strobogrammaticMap.containsKey(leftChar) || strobogrammaticMap.get(leftChar) != rightChar) {
returnfalse;
 }

left++;
right--;
 }

returntrue;
 }
}