CODE 67. Add Binary

版权声明：本文为博主原创文章，转载请注明出处，谢谢!

版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/10/07/2013-10-07-CODE 67 Add Binary/

访问原文「CODE 67. Add Binary」

Given two binary strings, return their sum (also a binary string).
For example,
a = "11"
b = "1"
Return "100".

public String addBinary(String a, String b) {
	// Note: The Solution object is instantiated only once and is reused by
	// each test case.
	char[] as = a.toCharArray();
	char[] bs = b.toCharArray();
	int i = as.length - 1;
	int j = bs.length - 1;
	int c = 0;
	StringBuilder sb = new StringBuilder();
	while (i >= 0 && j >= 0) {
		if (0 == c) {
			if ((as[i] == '0' && bs[j] == '1')
					|| (as[i] == '1' && bs[j] == '0')) {
				sb = sb.insert(0, '1');
				c = 0;
			} else if ((as[i] == '0' && bs[j] == '0')) {
				sb = sb.insert(0, '0');
				c = 0;
			} else {
				sb = sb.insert(0, '0');
				c = 1;
			}
		} else if (1 == c) {
			if ((as[i] == '0' && bs[j] == '1')
					|| (as[i] == '1' && bs[j] == '0')) {
				sb = sb.insert(0, '0');
				c = 1;
			} else if ((as[i] == '0' && bs[j] == '0')) {
				sb = sb.insert(0, '1');
				c = 0;
			} else {
				sb = sb.insert(0, '1');
				c = 1;
			}
		}
		i--;
		j--;
	}
	while (i >= 0) {
		if (0 == c) {
			sb = sb.insert(0, as[i]);
			c = 0;

		} else if (1 == c) {
			if (as[i] == '0') {
				sb = sb.insert(0, '1');
				c = 0;
			} else {
				sb = sb.insert(0, '0');
				c = 1;
			}
		}
		i--;
	}
	while (j >= 0) {
		if (0 == c) {
			sb = sb.insert(0, bs[j]);
			c = 0;

		} else if (1 == c) {
			if (bs[j] == '0') {
				sb = sb.insert(0, '1');
				c = 0;
			} else {
				sb = sb.insert(0, '0');
				c = 1;
			}
		}
		j--;
	}
	if (1 == c) {
		sb = sb.insert(0, '1');
	}
	return sb.toString();
}