题解 | #字符串合并处理#

const rl = require("readline").createInterface({
    input: process.stdin,
    output: process.stdout,
});

var iter = rl[Symbol.asyncIterator]();

const readline = async () => (await iter.next()).value;

void (async function () {
    while ((line = await readline())) {
        // 1.合并
        const initialArr = line.split(" ").join("");

        // 2.排序（按奇偶位置）
        const tempOddArr = [];
        const tempEvenArr = [];
        for (let i = 0; i < initialArr.length; i++) {
            let item = initialArr[i];
            if (i % 2 == 0) {
                tempEvenArr.push(item);
            } else {
                tempOddArr.push(item);
            }
        }
        tempEvenArr.sort();
        tempOddArr.sort();
        let targetStr = "";
        // 取最大长度
        const evenLen = tempEvenArr.length
        const oddLen = tempOddArr.length
        const len = Math.max(evenLen, oddLen)
        // 合并
        for (let i = 0; i < len; i++) {
            targetStr += (tempEvenArr[i] || '') + (tempOddArr[i] || '');
        }

        // 3.字符串转换（十六进制换成2进制或者十进制，再倒序，再转成大写）
        let targetArr = targetStr.split("");
        let result = [];
        for(let i = 0;i < targetArr.length; i++){
            let item = targetArr[i]
            let finalStr = item
             if (!isNaN(item) && item !== '') {
                // 数字转成2进制 倒序
                let num = Number(item).toString(2);
                num = num.padStart(4, 0).split("").reverse().join("");
                const tempItem = parseInt(num, 2);
                // 大于等于10 转16进制
                if (tempItem >= 10) {
                    finalStr = String.fromCharCode(tempItem + 55);
                } else {
                    finalStr = String(tempItem);
                }
            }

            // 小写字母
            if (/[a-f]/.test(item)) {
                let tempItem = parseInt(item, 16);
                const num = tempItem.toString(2);
                item = num.padStart(4, 0).split("").reverse().join("");
                tempItem = parseInt(item, 2);
                if (tempItem >= 10) {
                    // 有小写的需要转大写
                    finalStr = String.fromCharCode(tempItem + 55);
                } else {
                    finalStr = String(tempItem);
                }
            }


            // 大写字母
            if (/[A-F]/.test(item)) {
                let tempItem = item.charCodeAt() - 55;
                const num = tempItem.toString(2);
                item = num.padStart(4, 0).split("").reverse().join("");
                tempItem = parseInt(item, 2);
                if (tempItem >= 10) {
                    finalStr = String.fromCharCode(tempItem + 55);
                } else {
                    finalStr = String(tempItem);
                }
            }
            result.push(finalStr);

        }
        console.log(result.join(""));
    }
})();