415. Add Strings

[Tcdian]

415. Add Strings

给定两个字符串形式的非负整数 num1 和num2 ，计算它们的和。

Note

• num1 和 num2 的长度都小于 5100.
• num1 和 num2 都只包含数字 0-9.
• num1 和 num2 都不包含任何前导零。
• 你不能使用任何內建 BigInteger 库， 也不能直接将输入的字符串转换为整数形式。

[Tcdian]

Solution

• JavaScript Solution

/**
 * @param {string} num1
 * @param {string} num2
 * @return {string}
 */
var addStrings = function(num1, num2) {
    const maxLen = num1.length > num2.length ? num1.length + 1 : num2.length + 1;
    num1 = num1.padStart(maxLen, '0');
    num2 = num2.padStart(maxLen, '0');
    let result = '';
    let curry = 0;
    for (let i = maxLen - 1; i >= 0; i--) {
        const sum = Number(num1[i]) + Number(num2[i]) + curry
        result = sum % 10 + result;
        curry = Math.floor(sum / 10);
    }
    let separator = 0;
    while(separator !== result.length - 1 && result[separator] === '0') {
        separator++;
    }
    return result.slice(separator);
};

• TypeScript Solution

function addStrings(num1: string, num2: string): string {
    const maxLen = num1.length > num2.length ? num1.length + 1 : num2.length + 1;
    num1 = num1.padStart(maxLen, '0');
    num2 = num2.padStart(maxLen, '0');
    let result = '';
    let curry = 0;
    for (let i = maxLen - 1; i >= 0; i--) {
        const sum = Number(num1[i]) + Number(num2[i]) + curry
        result = sum % 10 + result;
        curry = Math.floor(sum / 10);
    }
    let separator = 0;
    while(separator !== result.length - 1 && result[separator] === '0') {
        separator++;
    }
    return result.slice(separator);
};