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function addStrings(num1: string, num2: string) {    // console.log("add",num1,num2)    if (        Array.prototype.every.call(num1, (s) => s === "0") &&        Array.prototype.every.call(num2, (s) => s === "0")    ) {        return "0";    }
    let i = num1.length - 1, j = num2.length - 1, add = 0;    const ans: number[] = [];    while (i >= 0 || j >= 0 || add != 0) {        const x: number = i >= 0 ? Number(num1.charAt(i)) : 0;        const y: number = j >= 0 ? Number(num2.charAt(j)) : 0;        const result = x + y + add;        ans.push(result % 10);        add = Math.floor(result / 10);        i -= 1;        j -= 1;    }    return ans.reverse().join("");}export default addStrings;