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
...
Example 1:
Input: "A"
Output: 1
Example 2:
Input: "AB"
Output: 28
Example 3:
Input: "ZY" Output: 701
满26进1
自己的思路:
{对应关系}
eg ABC = C对应的元素 + (26 + 对应的元素)+ (26 + 26 + 对应的元素)
总结规律:(位数 - 1)* 26 + 对应的元素
正确的思路:
//不是直接位数 * 26
//而是进位 * 26
从左边开始,逐个 * 26再往下
class Solution {
public int titleToNumber(String s) {
int res = 0;
for (int i = 0; i < s.length(); i++) {
res = res * 26 + (s.charAt(i) - 'A' + 1);
}
return res;
}
}