Add Binary

来源：互联网发布：js碰撞检测编辑：程序博客网时间：2024/04/30 03:49

Add Binary

Given two binary strings, return their sum (also a binary string).

For example,
a = "11"
b = "1"
Return "100".

本题的重点就是：

（1）补零对齐

（2）列出计算表

（3）注意最后一次进位

public class Solution {           static String[] lookupTable = {        "0+0+0=00",        "0+0+1=01",        "0+1+0=01",         "0+1+1=10",        "1+0+0=01",        "1+0+1=10",        "1+1+0=10",        "1+1+1=11",    };    static String lookup(char b1, char b2, char c) {        String formula = String.format("%c+%c+%c=", b1, b2, c);        for (String s : lookupTable) {            if (s.startsWith(formula)) {                return s.substring(s.indexOf("=") + 1);            }        }        throw new IllegalArgumentException();    }        static String zeroPad(String s, int length) {        while (s.length() < length) {            s = "0" + s;        }        return s;    }       static String addBinary(String s1, String s2) {        int length = Math.max(s1.length(), s2.length());        s1 = zeroPad(s1, length);        s2 = zeroPad(s2, length);        String result = "";        char carry = '0';        for (int i = length - 1; i >= 0; i--) {            String columnResult = lookup(s1.charAt(i), s2.charAt(i), carry);            result = columnResult.charAt(1) + result;            carry = columnResult.charAt(0);        }        if (carry == '1') {            result = carry + result;        }        return result;    }}

0 0