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// 987. Vertical Order Traversal of a Binary Tree
#include "leetcode.h"
/*
* given the 'root' of a binary tree, calcuate the vertical order traversal of
* the binary tree. for each node at position '(row, col)', its left and right
* children will be at positions '(row + 1, col - 1)' and '(row + 1, col + 1)'
* respectively. the root of the tree is at '(0, 0)'. the vertical order
* traversal of a binary tree is a list of top to bottom ordering for each
* column index starting from the leftmost column and ending on the rightmost
* column. there may be multiple nodes in the same row and same column. in such
* a case, sort these nodes by their values. return the vertical order traversal
* of the binary tree
*/
struct value {
int row;
int col;
int val;
};
int value_cmp(const void *left, const void *right) {
const struct value *l = (const struct value *)left;
const struct value *r = (const struct value *)right;
return l->col < r->col ? -1 : 1;
return l->row < r->row ? -1 : 1;
return l->val - r->val;
}
void helper(struct TreeNode *root, int row, int col, struct value **values,
size_t *values_size, size_t *values_cap) {
if (root) {
if (*values_size == *values_cap) {
*values_cap = (*values_cap) ? *values_cap * 2 : 16;
*values =
(struct value *)realloc(*values, *values_cap * sizeof(struct value));
}
(*values)[(*values_size)].col = col;
(*values)[(*values_size)].row = row;
(*values)[(*values_size)].val = root->val;
++*values_size;
helper(root->left, row + 1, col - 1, values, values_size, values_cap);
helper(root->right, row + 1, col + 1, values, values_size, values_cap);
}
}
int **verticalTraversal(struct TreeNode *root, int *returnSize,
int **returnColumnSizes) {
struct value *v = NULL;
size_t values_size = 0, values_cap = 0;
helper(root, 0, 0, &v, &values_size, &values_cap);
qsort(v, values_size, sizeof(struct value), &value_cmp);
int **ans = NULL;
*returnColumnSizes = NULL;
*returnSize = -1;
size_t cap = 0, sub_cap = 0;
int prev_col = INT_MIN;
for (size_t i = 0; i < values_size; ++i) {
if (v[i].col != prev_col) {
++(*returnSize);
if (*returnSize == cap) {
cap = cap ? cap * 2 : 4;
ans = (int **)realloc(ans, cap * sizeof(int *));
*returnColumnSizes =
(int *)realloc(*returnColumnSizes, cap * sizeof(int));
}
ans[*returnSize] = NULL;
(*returnColumnSizes)[(*returnSize)] = 0;
sub_cap = 0;
prev_col = v[i].col;
}
if ((*returnColumnSizes)[*returnSize] == sub_cap) {
sub_cap = sub_cap ? sub_cap * 2 : 4;
ans[*returnSize] =
(int *)realloc(ans[*returnSize], sub_cap * sizeof(int));
}
ans[*returnSize][(*returnColumnSizes)[*returnSize]++] = v[i].val;
}
++(*returnSize);
free(v);
return ans;
}
int main() {
struct TreeNode *root = treenode_create(1);
root->left = treenode_create(2);
root->right = treenode_create(3);
root->left->left = treenode_create(4);
root->left->right = treenode_create(5);
root->right->left = treenode_create(6);
root->right->right = treenode_create(7);
int returnSize, *returnColumnSizes;
int **vt = verticalTraversal(root, &returnSize, &returnColumnSizes);
for (int i = 0; i < returnSize; i++) {
for (int j = 0; j < returnColumnSizes[i]; j++)
printf("%d ", vt[i][j]); // expect: [[4],[2],[1,5,6],[3],[7]]
printf("\n");
}
for (int i = 0; i < returnSize; i++)
free(vt[i]);
free(vt), free(returnColumnSizes);
treenode_free(root);
}
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