zwfang · December 7, 2018 14:39 · Dec 7, 2018
diff --git a/addBinary.c b/addBinary.c
@@ -0,0 +1,57 @@
+//
+//  main.c
+//  addBinary
+//
+//  Created by fzw on 10/7/18.
+//  Copyright © 2018 n. All rights reserved.
+//
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+char * addBinary(char * a, char * b);
+
+int main(int argc, const char * argv[]) {
+    char * a = "11";
+    char * b = "11";
+    printf("%s\n", addBinary(a, b));
+    return 0;
+}
+
+char * addBinary(char * a, char * b) {
+    int i, lenA, lenB, len, temp = 0;
+    char * str;
+    lenA = (int)strlen(a);
+    lenB = (int)strlen(b);
+    len = lenA > lenB ? lenA: lenB;
+    str = (char *)malloc((len+2)*sizeof(char));
+    memset(str, 0, (len+2)*sizeof(char));
+
+    for (i = len; i >= 0 && lenA > 0 && lenB > 0; i--) {
+        *(str+i) = ((*(a + lenA-1) - '0') + (*(b + lenB-1) - '0') + temp)%2 + '0';
+        temp = ((*(a + lenA-1) - '0') + (*(b + lenB-1) - '0') + temp)/2;
+        lenA--;
+        lenB--;
+    }
+
+    if (lenA == 0) {
+        for (; lenB > 0; i--) {
+            *(str+i) = ((*(b + lenB-1) - '0') + temp) % 2 + '0';
+            temp = ((*(b + lenB-1) - '0') + temp)/ 2;
+            lenB--;
+        }
+    } else if (lenB == 0) {
+        for (; lenA > 0; i--) {
+            *(str+i) = ((*(a + lenA-1) - '0') + temp) % 2 + '0';
+            temp = ((*(a + lenA-1) - '0') + temp) / 2;
+            lenA--;
+        }
+    }
+    if (temp == 1) {
+        *(str+i) = temp + '0';
+        return str + i;
+    }
+
+    return str + i + 1;
+}