//列名元素集
const COL_ABC = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" ];

/**
 * 十進(jìn)制的數(shù)化為k進(jìn)制的數(shù)【返回?cái)?shù)組的index=0位置是最高位】（取k取余法）
 * @num 10進(jìn)制數(shù)
 * @k k
 * @returns k進(jìn)制數(shù)序列
 */
function ckqy(num,k) {
    let y = [];
    while (num > 0) {
        let s = Math.floor(num / k);
        let _y = num % k;
        //console.log(num + " ÷ " + k + " ＝ " + s + " ··· " + _y);
        if (s == 0)
        {
            y.push(num);
            num = 0;
        }
        else
        {
            y.push(_y);
            num = s;
        }
    }
    return y.reverse();
}

/**
 * k進(jìn)制的數(shù)化為十進(jìn)制的數(shù)(乘冪相加法)
 * @kArray k進(jìn)制數(shù)序列
 * @k k
 * @returns 十進(jìn)制的數(shù)
 */
function kTo10(kArray,k){
    let v10=0;
    let kArrayLen=kArray.length;
    for(let ind=0; ind<kArrayLen; ind++){
        v10 += kArray[ind] * Math.pow(k,kArrayLen - 1 - ind);
    }
    return v10;
}

/**
 * 獲取列名
 * @colIndex 列序號(hào)（從0開(kāi)始）
 * @returns 列名
 */
function getColName(colIndex)
{
    if(colIndex < 0){
        return '';
    }
    let colNames =[];
    // 等于0 和 大于25 的 colIndex 
    let isAdd1 = colIndex > 25 || colIndex < 1 ;
    //10進(jìn)制轉(zhuǎn)26進(jìn)制
    let kArray = ckqy(colIndex + (isAdd1 ? 1: 0), 26);
    for (let i = 0; i < kArray.length; i++)
    {
        colNames.push(COL_ABC[ kArray[i]- (isAdd1 ? 1: 0) ] || '');
    }
    return colNames.join('');
}

/**
 * 獲取列名對(duì)應(yīng)ABC數(shù)據(jù)序號(hào)
 * @colIndex 列序號(hào)（從0開(kāi)始）
 * @returns 
 */
function getABCIndex(colName){
    let kArray = [];
    let colNames=colName.split('');
    for(let ind=0;ind <colNames.length;ind++){
        let k = COL_ABC.indexOf(colNames[ind]);
        if(k > -1){
            kArray.push(k);
        }
    }
    return kArray;
}
/**
 * 獲取列序號(hào)
 * @colIndex 列名
 * @returns 列序號(hào)（從0開(kāi)始）
 */
function getColIndex(colName)
{
    if(!colName){
        return -1;
    }
    // colName 轉(zhuǎn) COL_ABC 序號(hào)
    let kArray = getABCIndex(colName);
    let kArrayLen=kArray.length;
    if(kArrayLen==0){
        return -1;
    }
    let colIndex =0;
    for(let ind=0;ind <kArrayLen;ind++){
        let k = kArray[ind] + (  (kArrayLen-1)  == ind ? 0:1);
        let p =  kArrayLen-1-ind;
        //console.log(k+' * Math.pow(26,'+p+');');
        colIndex += k * Math.pow(26,p);
    }
    return colIndex;
}

let _colName = 'ABC';
let colIndex=getColIndex(_colName);
console.log(colIndex);
let colName = getColName(colIndex);
console.log(colName);
console.log(_colName  == colName  );