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ExcelSheetColumnNumber.java
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ExcelSheetColumnNumber.java
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package answer;
public class ExcelSheetColumnNumber {
public static void main(String[] args) {
ExcelSheetColumnNumber myMain = new ExcelSheetColumnNumber();
String[] testCase = { "A", "B", "C", "X", "Y", "Z", "AA", "AB", "ZZ",
"AAA", "AAB" };
for (String str : testCase) {
System.out.println(str + " Answer: " + myMain.titleToNumber(str));
System.out.println(str + " Answer: " + myMain.bestAlgorithm(str));
}
}
public int titleToNumber(String s) {
if (s.isEmpty())
return 0;
int rtn = 0;
for (int i = s.length() - 1; i >= 0; --i) {
char theWord = s.charAt(i);
int theNumber = getNumberFrom(theWord);
rtn += Math.pow(26d, Double.valueOf("" + reverse(s.length(), i)))
* theNumber;
}
return rtn;
}
private int getNumberFrom(char theWord) {
// 為了要讓Z能夠正確顯示,需要另外做判斷
return ((int) theWord - 64) == 26 ? 26 : (int) theWord - 64;
}
private int reverse(int length, int i) {
return length - 1 - i;
}
// Ref: https://discuss.leetcode.com/topic/36499/my-2ms-java-solution/2
public int bestAlgorithm(String s) {
int result = 0;
for (int i = 0; i < s.length(); i++) {
result *= 26;
result += ((s.charAt(i) - 'A') + 1);
}
return result;
}
}