add find-all-anagrams-in-a-string.c

Author: lightmen

c/hash-table/find-all-anagrams-in-a-string.c

@@ -0,0 +1,36 @@
+/**
+ * Return an array of size *returnSize.
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+int* findAnagrams(char* s, char* p, int* returnSize) {
+    int *ret;
+    int hp[256] = {0};
+    int i;
+    int ls, lp;
+    int count, index = 0;
+
+    ls = strlen(s);
+    lp = strlen(p);
+    count = lp;
+    ret = malloc(sizeof(int) * ls);
+
+    for(i = 0; i < lp; ++i)
+        hp[p[i]]++;
+
+    for(i = 0; i < ls; ++i){
+        if(hp[s[i]] > 0)
+            count--;
+        hp[s[i]]--;
+        if(i >= lp){
+            if(hp[s[i - lp]] >= 0)
+                count++;
+            hp[s[i - lp]]++;
+        }
+
+        if(count == 0)
+            ret[index++] = i - lp + 1;
+    }
+
+    *returnSize = index;
+    return ret;
+}