javascript
/**
* @param {string} columnTitle
* @return {number}
*/
var titleToNumber = function (columnTitle) {
let result = 0
const len = columnTitle.length
const map = { A: 1, B: 2, C: 3, D: 4, E: 5, F: 6, G: 7, H: 8, I: 9, J: 10, K: 11, L: 12, M: 13, N: 14, O: 15, P: 16, Q: 17, R: 18, S: 19, T: 20, U: 21, V: 22, W: 23, X: 24, Y: 25, Z: 26 }
if (len === 1) {
return map[columnTitle]
}
for (let i = len - 1; i >= 0; i--) {
result += map[columnTitle[i]] * 26 ** (len - i - 1)
}
return result
}