Add C version for Leetcode202 passed Leetcode submission

problems/0202.快乐数.md

@@ -315,5 +315,75 @@ class Solution {
 }
 ```
 
+C:
+```C
+typedef struct HashNodeTag {
+    int key;   /* num  */
+    struct HashNodeTag *next;
+}HashNode;
+
+/* Calcualte the hash key */
+static inline int hash(int key, int size) {
+    int index = key % size;
+    return (index > 0) ? (index) : (-index);
+}
+
+/* Calculate the sum of the squares of its digits*/
+static inline int calcSquareSum(int num) {
+    unsigned int sum = 0;
+    while(num > 0) {
+        sum += (num % 10) * (num % 10);
+        num = num/10; 
+    }
+    return sum;
+}
+
+#define HASH_TABLE_SIZE     (32)
+
+bool isHappy(int n){
+    int sum = n;
+    int index = 0;
+    bool bHappy = false;
+    bool bExit = false;
+    /* allocate the memory for hash table with chaining method*/
+    HashNode ** hashTable = (HashNode **)calloc(HASH_TABLE_SIZE, sizeof(HashNode));
+    
+    while(bExit == false) {
+        /* check if n has been calculated */
+        index = hash(n, HASH_TABLE_SIZE);
+
+        HashNode ** p = hashTable + index;
+
+        while((*p) && (bExit == false)) {
+            /* Check if this num was calculated, if yes, this will be endless loop */
+            if((*p)->key == n) { 
+                bHappy = false;
+                bExit = true;
+            }
+            /* move to next node of the same index */
+            p = &((*p)->next);
+        }
+
+        /* put n intot hash table */
+        HashNode * newNode = (HashNode *)malloc(sizeof(HashNode));
+        newNode->key = n;
+        newNode->next = NULL;
+
+        *p = newNode;
+
+        sum = calcSquareSum(n);
+        if(sum == 1) {
+            bHappy = true;
+            bExit = true;
+        }
+        else {
+            n = sum;
+            
+        }
+    }
+
+    return bHappy;
+}
+```
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