Given two binary strings, return their sum (also a binary string).
For example,
a = "11"
b = "1"
Return "100".
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public class Solution {
public String addBinary(String a, String b) {
if (a == null || a.length() == 0) {
return b;
}
if (b == null || b.length() == 0) {
return a;
}
int addBits = Math.min(a.length(), b.length());
StringBuffer sb = new StringBuffer();
int bitPlus = 0;
for (int i = 0; i < addBits; i++) {
int aBit = a.charAt(a.length() - 1 - i) - '0';
int bBit = b.charAt(b.length() - 1 - i) - '0';
int cur = aBit + bBit + bitPlus;
bitPlus = cur / 2;
cur = cur % 2;
sb.insert(0, String.valueOf(cur));
}
return doOther( a, b, addBits, bitPlus, sb);
}
public String doOther(String a, String b, int addBits,int bitPlus,StringBuffer sb) {
if (b.length() > a.length()) {
doOther( b, a, addBits, bitPlus, sb);
} else {
for (int i = addBits; i < a.length();i++)
{
int aBit = a.charAt(a.length() - 1 - i ) - '0';
int cur = aBit + bitPlus;
bitPlus = cur / 2;
cur = cur % 2;
sb.insert(0,String.valueOf(cur));
}
if (bitPlus == 1) {
sb.insert(0,"1");
}
return sb.toString();
}
return sb.toString();
}
}