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A regular expression can be used to validate if a string is a valid number by matching patterns that define valid numbers. This pattern matches integers with optional signs, decimals, and scientific notation.
Time Complexity: O(n) due to scanning each character in the string.
Space Complexity: O(1) since we're using a fixed-size pattern.
1function isNumber(s) {
2 const pattern = /^[\+-]?((\d+\.?|\.\d)\d*)([eE][\+-]?\d+)?$/;
3 return pattern.test(s);
4}
5console.log(isNumber('53.5e93')); // true
6console.log(isNumber('1a')); // falseJavaScript’s RegExp object method test is used for matching the string against a regex pattern that specifies valid numerical forms.
This approach involves parsing the string based on its characters and their positions. By iterating through the string, the method confirms whether it forms a valid number pattern based on segment rules.
Time Complexity: O(n) where n is the length of the string.
Space Complexity: O(1) using variables to track state.
1def
This Python approach iterates through the string, ensuring all rules for a valid number are adhered to based on the position and current context of each character.