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// 652. Find Duplicate Subtrees
#include "./lib/uthash/src/uthash.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* given 'root' of a binary tree, return all duplicate subtrees. for each kind
* of duplicate, only return the root node of any one of them. two trees are
* duplicate if they have the same structure with the same node values.
*/
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
};
typedef struct {
char *r_key;
int cnt;
UT_hash_handle hh;
} h_elem;
char *dfs(struct TreeNode *root, h_elem **map, struct TreeNode **ans,
int *idx) {
h_elem *tmp;
if (!root) {
char *r = calloc(sizeof(char), 2);
strcpy(r, "N");
return r;
}
char *l_str = dfs(root->left, map, ans, idx);
char *r_str = dfs(root->right, map, ans, idx);
int c_len = strlen(l_str) + strlen(r_str) + 7;
char *ans_str = calloc(sizeof(char), c_len);
sprintf(ans_str, "%d, %s, %s\n", root->val, l_str, r_str);
HASH_FIND_STR(*map, ans_str, tmp);
if (tmp) {
tmp->cnt++;
if (tmp->cnt == 2)
ans[(*idx)++] = root;
} else {
h_elem *tmp = malloc(sizeof(h_elem));
tmp->r_key = ans_str;
tmp->cnt = 1;
HASH_ADD_KEYPTR(hh, *map, tmp->r_key, strlen(tmp->r_key), tmp);
}
return ans_str;
}
struct TreeNode **findDuplicateSubtrees(struct TreeNode *root,
int *returnSize) {
struct TreeNode **ans = malloc(sizeof(struct TreeNode *) * 250);
*returnSize = 0;
h_elem *map = NULL;
dfs(root, &map, ans, returnSize);
return ans;
}
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