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export default function maximumSwap(num: number): number {    const charArray = [..."" + num];    const n = charArray.length;    let maxIdx = n - 1;    let idx1 = -1, idx2 = -1;    for (let i = n - 1; i >= 0; i--) {        if (charArray[i] > charArray[maxIdx]) {            maxIdx = i;        } else if (charArray[i] < charArray[maxIdx]) {            idx1 = i;            idx2 = maxIdx;        }    }    if (idx1 >= 0) {        [charArray[idx1], charArray[idx2]] = [charArray[idx2], charArray[idx1]];        return parseInt(charArray.join(""));    } else {        return num;    }}