Excel Sheet Column Number, sheetcolumn

Excel Sheet Column Number, sheetcolumn

This article is in the study of the summary, welcome to reprint but please note the Source: http://blog.csdn.net/pistolove/article/details/42290079

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

    A -> 1    B -> 2    C -> 3    ...    Z -> 26    AA -> 27    AB -> 28 

Ideas:

(1) The question is to give the character of the corresponding column in Excel to find the corresponding integer of this character.

(2) This simple question examines the question of "Twenty-six hexadecimal" (not actually twenty-six hexadecimal ). It is not difficult to find that when the value exceeds 26, it will change like decimal. I will not explain it here.

(3) Taking into account the simplicity and efficiency, the integer corresponding to the 26 characters is directly stored in a Map. It must be noted that the power () method of the Math class is used in the algorithm. This method is a power function.

For example, for the character "ABC", the solution process is:

Count = 0 + 1 * Math. power (26, 2) = 676;

Count = 676 + 2 * Math. power (26, 1) = 728;

Count = 728 + 3 * Math. power (26, 0) = 731;

(4) I hope this article will help you.

The algorithm code is implemented as follows:

public static int titleToNumber(String s) {Map<String, Integer> all = new HashMap<String, Integer>();all.put("A", 1);all.put("B", 2);all.put("C", 3);all.put("D", 4);all.put("E", 5);all.put("F", 6);all.put("G", 7);all.put("H", 8);all.put("I", 9);all.put("J", 10);all.put("K", 11);all.put("L", 12);all.put("M", 13);all.put("N", 14);all.put("O", 15);all.put("P", 16);all.put("Q", 17);all.put("R", 18);all.put("S", 19);all.put("T", 20);all.put("U", 21);all.put("V", 22);all.put("W", 23);all.put("X", 24);all.put("Y", 25);all.put("Z", 26);if (s == null)return -1;int len = s.length();int sum = 0;int power = len - 1;for (int i = 0; i < len; i++) {int curr = all.get(String.valueOf(s.charAt(i)));sum += curr * Math.pow(all.size(), power);power--;}return sum;}