update

1 files changed, 75 insertions, 0 deletions

diff --git a/Computer_Science/leetcode/67-add_binary.c b/Computer_Science/leetcode/67-add_binary.c
new file mode 100644
index 0000000..48e4744
--- /dev/null
+++ b/Computer_Science/leetcode/67-add_binary.c
@@ -0,0 +1,75 @@
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+char* addBinary(char* a, char* b) {
+	int lenA = strlen(a);
+	int lenB = strlen(b);
+
+	int len = MAX(lenA, lenB) + 1;
+	char* result = malloc(sizeof(char) * (len + 1));
+	result[len--] = '\0';
+	char in = '0';
+	int sum = 0;
+
+	lenA--;
+	lenB--;
+
+	if(len == 0) return "0";
+	
+	while(lenA >= 0 && lenB >=0) {
+		sum = a[lenA] + b[lenB] + in - 3 * '0';
+		switch(sum) {
+		case 0:
+			in = '0';
+			result[len] = '0';
+			break;
+		case 1:
+			in = '0';
+			result[len] = '1';
+			break;
+		case 2:
+			in = '1';
+			result[len] = '0';
+			break;
+		case 3:
+			in = '1';
+			result[len] = '1';
+			break;
+		}
+		lenA--;
+		lenB--;
+		len--;
+	}
+
+	while(lenA >= 0) {
+		if(in == '0') {
+			result[len] = a[lenA];
+		} else if(a[lenA] == '1') {
+			result[len] = '0';
+			in = '1';
+		} else {
+			result[len] = '1';
+			in = '0';
+		}
+		lenA--;
+		len--;
+	}
+
+	while(lenB >= 0) {
+		if(in == '0') {
+			result[len] = b[lenB];
+		} else if(b[lenB] == '1') {
+			result[len] = '0';
+			in = '1';
+		} else {
+			result[len] = '1';
+			in = '0';
+		}
+		lenB--;
+		len--;
+	}
+
+	if(in == '0')
+		return result + 1;
+
+	*result = '1';
+	return result;
+}