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begeekmyfriend · begeekmyfriend · commit 85243ba2f613 · 2020-07-17T12:18:01.000+08:00
Signed-off-by: begeekmyfriend &lt;begeekmyfriend@gmail.com&gt;
diff --git a/002_add_two_numbers/add_two_numbers.c b/002_add_two_numbers/add_two_numbers.c
@@ -17,7 +17,6 @@ static struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2)
     dummy.next = p;
     while (l1 != NULL || l2 != NULL) {
         int sum = 0;
-        int last_carry = carry;
 
         if (l1 != NULL) {
             sum += l1->val;
@@ -34,7 +33,7 @@ static struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2)
             l2 = l2->next;
         }
 
-        sum += last_carry;
+        sum += carry;
         carry = sum / 10;
         p->val = sum % 10;
         prev = p;
diff --git a/003_longest_substring_without_repeat/longest_substring_without_repeat.c b/003_longest_substring_without_repeat/longest_substring_without_repeat.c
@@ -15,10 +15,10 @@ static int lengthOfLongestSubstring(char *s)
             len++;
         } else {
             if (index - offset[*s] > len) {
-                /* not include in substring, go on increasing */
+                /* not included in sliding window, go on increasing */
                 len++;
             } else {
-                /* count from scratch */
+                /* repetition in sliding window, count from scratch */
 	        len = index - offset[*s];
             }
         }
diff --git a/007_reverse_integer/reverse_integer.c b/007_reverse_integer/reverse_integer.c
@@ -2,20 +2,24 @@
 #include <stdlib.h>
 #include <limits.h>
 
+
 static int reverse(int x)
 {
-    int y = 0;
+    int n = 0;
     while (x != 0) {
-        int n = x % 10;
-        // Checking the over/underflow.
-        // Actually, it should be y>(INT_MAX-n)/10, but n/10 is 0, so omit it.
-        if (y > INT_MAX / 10 || y < INT_MIN / 10) {
+        int r = x % 10;
+        /* Checking the over/underflow. */
+        if (n > INT_MAX / 10 || (n == INT_MAX / 10 && r > 7)) {
+            return 0;
+        }
+        if (n < INT_MIN / 10 || (n == INT_MIN / 10 && r < -8)) {
             return 0;
         }
-        y = y * 10 + n;
+
+        n = n * 10 + r;
         x /= 10;
     }
-    return y;
+    return n;
 }
 
 #define TEST(n, e)  printf("%12d  =>  %-12d  %s!\n",  n, reverse(n),  e == reverse(n)?"passed":"failed")
diff --git a/008_atoi/atoi.c b/008_atoi/atoi.c
@@ -1,16 +1,35 @@
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <limits.h>
 
+
 static int myAtoi(char* str)
 {
     char *s;
-    int n = 0, sign = 0;
+    long n = 0;
+    int sign = 0;
 
     while (*str == ' ' || *str == '\t') {
         str++;
     }
 
+    if (*str == '-') {
+        if (isdigit(*++str)) {
+            sign = 1;
+        } else {
+            return 0;
+        }
+    }
+
+    if (*str == '+') {
+        if (isdigit(*++str)) {
+            sign = 0;
+        } else {
+            return 0;
+        }
+    }
+
     for (s = str; *s != '\0'; s++) {
         if (isdigit(*s)) {
             int d = *s - '0';
@@ -26,10 +45,6 @@ static int myAtoi(char* str)
                 }
             }
             n = n * 10 + d;
-        } else if (*s == '-' && isdigit(*(s + 1)) && (n == 0)) {
-            sign = 1;
-        } else if (*s == '+' && isdigit(*(s + 1)) && (n == 0)) {
-            sign = 0;
         } else {
             break;
         }
diff --git a/009_palindrome_number/palindrome_number.c b/009_palindrome_number/palindrome_number.c
@@ -2,14 +2,23 @@
 #include <stdlib.h>
 #include <stdbool.h>
 
+
 static int reverse(int x)
 {
-    int y = 0;
-    while (x) {
-        y = y * 10 + x % 10;
+    int n = 0;
+    while (x != 0) {
+        int r = x % 10;
+        /* Checking the over/underflow. */
+        if (n > INT_MAX / 10 || (n == INT_MAX / 10 && r > 7)) {
+            return 0;
+        }
+        if (n < INT_MIN / 10 || (n == INT_MIN / 10 && r < -8)) {
+            return 0;
+        }
+        n = n * 10 + r;
         x /= 10;
     }
-    return y;
+    return n;
 }
 
 static bool isPalindrome(int x)

Original file line number	Diff line number	Diff line change
`@@ -15,10 +15,10 @@ static int lengthOfLongestSubstring(char *s)`
`15`	`15`	`len++;`
`16`	`16`	`} else {`
`17`	`17`	`if (index - offset[*s] > len) {`
`18`		`- /* not include in substring, go on increasing */`
	`18`	`+ /* not included in sliding window, go on increasing */`
`19`	`19`	`len++;`
`20`	`20`	`} else {`
`21`		`- /* count from scratch */`
	`21`	`+ /* repetition in sliding window, count from scratch */`
`22`	`22`	`len = index - offset[*s];`
`23`	`23`	`}`
`24`	`24`	`}`