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begeekmyfriend · begeekmyfriend · commit 4d550a5ad982 · 2020-06-07T08:28:48.000+08:00
Signed-off-by: begeekmyfriend &lt;begeekmyfriend@gmail.com&gt;
diff --git a/021_merge_two_sorted_lists/merge_lists.c b/021_merge_two_sorted_lists/merge_lists.c
@@ -12,7 +12,7 @@ static struct ListNode* mergeTwoLists(struct ListNode* l1, struct ListNode* l2)
     struct ListNode *prev = &dummy;
     dummy.next = l1;
 
-    while (l1 != NULL || l2 != NULL) {
+    while (l1 != NULL && l2 != NULL) {
         if (l1->val <= l2->val) {
             prev = l1;
             l1 = l1->next;
diff --git a/239_sliding_window_maximum/slide_window.c b/239_sliding_window_maximum/slide_window.c
@@ -13,16 +13,19 @@ int* maxSlidingWindow(int* nums, int numsSize, int k, int* returnSize)
     int *results = malloc((numsSize - k + 1) * sizeof(int));
 
     for (i = 0; i < numsSize; i++) {
-        /* monotonous decreasing */
+        /* keep the elements in slide window monotonous decreasing */
         while (tail > head && nums[i] >= nums[indexes[tail - 1]]) {
+            /* squeeze out the previous smaller ones */
             tail--;
         }
-        indexes[tail++] = i;
 
+        /* Pipe: first in last out */
+        indexes[tail++] = i;
         if (indexes[head] <= i - k) {
             head++;
         }
 
+        /* k - 1 is the end of the first sliding window */
         if (i >= k - 1) {
             results[count++] = nums[indexes[head]];
         }

Original file line number	Diff line number	Diff line change
`@@ -13,16 +13,19 @@ int* maxSlidingWindow(int* nums, int numsSize, int k, int* returnSize)`
`13`	`13`	`int results = malloc((numsSize - k + 1) sizeof(int));`
`14`	`14`
`15`	`15`	`for (i = 0; i < numsSize; i++) {`
`16`		`- /* monotonous decreasing */`
	`16`	`+ /* keep the elements in slide window monotonous decreasing */`
`17`	`17`	`while (tail > head && nums[i] >= nums[indexes[tail - 1]]) {`
	`18`	`+ /* squeeze out the previous smaller ones */`
`18`	`19`	`tail--;`
`19`	`20`	`}`
`20`		`- indexes[tail++] = i;`
`21`	`21`
	`22`	`+ /* Pipe: first in last out */`
	`23`	`+ indexes[tail++] = i;`
`22`	`24`	`if (indexes[head] <= i - k) {`
`23`	`25`	`head++;`
`24`	`26`	`}`
`25`	`27`
	`28`	`+ /* k - 1 is the end of the first sliding window */`
`26`	`29`	`if (i >= k - 1) {`
`27`	`30`	`results[count++] = nums[indexes[head]];`
`28`	`31`	`}`