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// 2096. Step-By-Step Directions From a Binary Tree Node to Another
#include "leetcode.h"
/*
* you are given the 'root' of a binary tree with 'n' nodes. each node is
* uniquely assigned a value from 1 to 'n'. you are also given an integer
* 'startValue' representing the value of the stat node 's', nd a different
* integer 'destValue' representing the value of the destination node 't', find
* the shortest path from node 's' to node 't'. generate step by step directions
* of such path as a string consisting only of upper case letters L R and U,
* return the step by step directions of the shortest path.
*/
void reverse_str(char *s) {
int tmp;
for (int i = 0; i < strlen(s) / 2; i++) {
tmp = s[i];
s[i] = s[strlen(s) - 1 - i];
s[strlen(s) - 1 - i] = tmp;
}
}
int find_node(struct TreeNode *root, int val, char *s) {
if (!root)
return 0;
if (root->val == val)
return 1;
int res = find_node(root->left, val, s);
if (res == 1) {
strcat(s, "L");
return 1;
}
res = find_node(root->right, val, s);
if (res == 1) {
strcat(s, "R");
return 1;
}
return 0;
}
#define MAX_SZ 10001
char *getDirections(struct TreeNode *root, int startValue, int destValue) {
char str_s[MAX_SZ] = "", str_d[MAX_SZ] = "";
char *ans = (char *)malloc(MAX_SZ * sizeof(char));
ans[0] = '\0';
find_node(root, startValue, str_s);
find_node(root, destValue, str_d);
int s_idx = strlen(str_s) - 1, d_idx = strlen(str_d) - 1;
while (s_idx >= 0 && d_idx >= 0) {
if (str_s[s_idx] == str_d[d_idx]) {
str_s[s_idx] = '\0';
str_d[d_idx] = '\0';
s_idx--, d_idx--;
} else
break;
}
for (int i = 0; i <= s_idx; i++)
strcat(ans, "U");
reverse_str(str_d);
strcat(ans, str_d);
return ans;
}
int main() {
struct TreeNode *root = treenode_create(5);
root->left = treenode_create(1);
root->right = treenode_create(2);
root->left->left = treenode_create(3);
root->right->left = treenode_create(6);
root->right->right->right = treenode_create(4);
printf("%s\n", getDirections(root, 3, 6)); // expect: UURL
}
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