case fix for 0028 and 0066

Author: Zuchen Liu

0028_implement_strstr/strstr.c

@@ -78,6 +78,10 @@ static int strStr(char *haystack, char *needle)
     unsigned int hlen = strlen(haystack);
     unsigned int nlen = strlen(needle);
 
+    // when haystack is shorter than needle, should return -1
+    if(hlen < nlen)
+        return -1;
+
     /* Brute force */
     /* Corner condition: imagine nlen = 1 and it equals i < hlen */
     for (i = 0; i < hlen - nlen + 1; i++) {

0066_plus_one/plus_one.c

@@ -11,9 +11,15 @@ static int* plusOne(int* digits, int digitsSize, int* returnSize)
     int i, j, len = 0, carry = 1;
     int *result = malloc((digitsSize + 1) * sizeof(int));
     for (i = digitsSize - 1; i >= 0 || carry; i--) {
-        int n = digits[i] + carry;
-        result[len++] = n % 10;
-        carry = n / 10;
+        if(i >= 0){
+            int n = digits[i] + carry;
+            result[len++] = n % 10;
+            carry = n / 10;
+        } else {
+            // add case like [9]
+            result[len++] = 1;
+            carry = 0;
+        }
     }
 
     for (i = 0, j = len - 1; i < j; i++, j--) {