diff --git a/0076_minimum_window_substring/window_substring.c b/0076_minimum_window_substring/window_substring.c
index 41f5d0b..792e898 100644
--- a/0076_minimum_window_substring/window_substring.c
+++ b/0076_minimum_window_substring/window_substring.c
@@ -18,31 +18,31 @@ static char *minWindow(char *s, char *t)
     int i, j, count[256] = { 0 };
     int slen = strlen(s);
     int tlen = strlen(t);
+    /* edges of sliding window */
+    int l = 0, r = 0;
+    int min_len = slen + 1;
+    int start = 0;
+    int chars_to_meet = 0;
+
     for (i = 0; i < tlen; i++) {
         count[t[i]]++;
     }
 
-    /* edges of sliding window */
-    int lo = 0, hi = 0;
-    int min_len = slen + 1;
-    int start = 0;
-    int chars_to_meet = tlen;
-    while (hi < slen) {
-        if (--count[s[hi++]] >= 0) {
+    while (r < slen) {
+        if (--count[s[r++]] >= 0) {
             /* pattern found */
-            chars_to_meet--;
+            chars_to_meet++;
         }
 
-        while (chars_to_meet == 0) {
-            if (hi - lo < min_len) {
-                min_len = hi - lo;
-                start = lo;
+        while (chars_to_meet == tlen) {
+            if (r - l < min_len) {
+                min_len = r - l;
+                start = l;
             }
 
             /* Chars with negative count are not included in the pattern string */
-            if (++count[s[lo++]] > 0) {
-                /* chars_to_meet == 1 */
-                chars_to_meet++;
+            if (++count[s[l++]] > 0) {
+                chars_to_meet--;
             }
         }
     }
diff --git a/0438_find_all_anagrams_in_a_string/anagrams_in_string.c b/0438_find_all_anagrams_in_a_string/anagrams_in_string.c
index 9a3ec67..f780591 100644
--- a/0438_find_all_anagrams_in_a_string/anagrams_in_string.c
+++ b/0438_find_all_anagrams_in_a_string/anagrams_in_string.c
@@ -5,23 +5,26 @@
 /**
  * Note: The returned array must be malloced, assume caller calls free().
  */
-int* findAnagrams(char * s, char * p, int* returnSize){
+int* findAnagrams(char * s, char * p, int* returnSize)
+{
     *returnSize = 0;
     int *res = malloc(11000 * sizeof(int));
     int i, pat_len = 0;
     int count[128] = { 0 };
+    int l = 0, r = 0, len = 0;
+
     for (i = 0; p[i] != '\0'; i++) {
         count[p[i]]++;
     }
     pat_len = i;
 
-    int l = 0, r = 0, len = 0;
     while (s[r] != '\0') {
         if (--count[s[r++]] >= 0) {
             len++;
         }
-        if (r - l >= pat_len) {
-            if (len == pat_len) {
+
+        while (len >= pat_len) {
+            if (r - l == pat_len) {
                 res[(*returnSize)++] = l;
             }
             if (++count[s[l++]] > 0) {
diff --git a/0516_longest_palindromic_subsequence/lps.c b/0516_longest_palindromic_subsequence/lps.c
index b8518b9..9972a01 100644
--- a/0516_longest_palindromic_subsequence/lps.c
+++ b/0516_longest_palindromic_subsequence/lps.c
@@ -13,6 +13,9 @@ int longestPalindromeSubseq(char * s)
     int i, j, k;
     int len = strlen(s);
     int **dp = malloc(len * sizeof(int *));
+
+    /* The dp array indicates the length of palindrome subsequence of
+     * nums[i...j] */
     for (i = 0; i < len; i++) {
         dp[i] = malloc(len * sizeof(int));
         memset(dp[i], 0, len * sizeof(int));
diff --git a/0567_permutation_in_string/permutation_in_string.c b/0567_permutation_in_string/permutation_in_string.c
index a20fa55..bdb4ea8 100644
--- a/0567_permutation_in_string/permutation_in_string.c
+++ b/0567_permutation_in_string/permutation_in_string.c
@@ -6,19 +6,21 @@
 
 bool checkInclusion(char * s1, char * s2)
 {
-    int i, count[128] = { -1 }, pat_len = 0;
+    int i, count[128] = { 0 }, pat_len;
+    int l = 0, r = 0, len = 0;
+
     for (i = 0; s1[i] != '\0'; i++) {
         count[s1[i]]++;
-        pat_len++;
     }
+    pat_len = i;
 
-    int l = 0, r = 0, len = 0;
     while (s2[r] != '\0') {
         if (--count[s2[r++]] >= 0) {
             len++;
         }
-        while (r - l >= pat_len) {
-            if (len == pat_len) {
+
+        while (len >= pat_len) {
+            if (r - l == pat_len) {
                 return true;
             }
             if (++count[s2[l++]] > 0) {