package com.leetcode.string;

import javax.lang.model.element.NestingKind;

/**

* Created by charles on 4/10/17.

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

For example,

a = "11"

b = "1"

Return "100".

*/

public class AddBinary_67 {

public String addBinary(String a, String b) {

int i = a.length() - 1, j = b.length() - 1;

int carry = 0;

StringBuilder sb = new StringBuilder();

int val = 0;

int aVal = 0, bVal = 0;

while (i >= 0 || j >= 0) {

if (i >= 0) {

aVal = a.charAt(i) - '0';

} else {

aVal = 0;

}

if (j >= 0) {

bVal = b.charAt(j) - '0';

} else {

bVal = 0;

}

val = aVal ^ bVal;

sb.insert(0, (val ^ carry));

carry = (aVal + bVal + carry) / 2;

i--;

j--;

}

if (carry != 0) {

sb.insert(0, carry);

}

return sb.toString();

}

public String addBinaryII(String a, String b) {

int i = a.length() - 1, j = b.length() - 1;

int carry = 0;

int aVal = 0, bVal = 0;

StringBuilder sb = new StringBuilder();

while (i >= 0 || j >= 0) {

aVal = i>=0 ? a.charAt(i) - '0' : 0;

bVal = j>=0 ? b.charAt(j) - '0' : 0;

sb.insert(0, aVal ^ bVal ^ carry);

carry = (aVal + bVal + carry) >> 1;

i--;

j--;

}

if (carry != 0) {

sb.insert(0, carry);

}

return sb.toString();

}

public static void main(String[] args) {

AddBinary_67 a = new AddBinary_67();

String s1 = "111";

String s2 = "1";

System.out.println(a.addBinary(s1, s2));

}

}