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// 2471. Minimum Number of Operations to Sort a Binary Tree by Level
#include "leetcode.h"
/*
* you are given the 'root' of a binary tree with unique values. in one
* operation, you can choose any two nodes at the same level and swap their
* values. return the minimum number of operations needed to make the values at
* each level sorted in a strictly increasing order. the level of a node is the
* number of edges along the path between it and the root node.
*/
#define MAX_SIZE 34472
struct node_idx {
struct TreeNode *node;
int idx;
};
int cmp(const void *a, const void *b) {
struct node_idx *aa = (struct node_idx *)a;
struct node_idx *bb = (struct node_idx *)b;
if ((*aa).node->val > (*bb).node->val)
return 1;
return -1;
}
int minimumOperations(struct TreeNode *root) {
struct node_idx nodes[MAX_SIZE], new[MAX_SIZE];
new[0].node = root;
int len = 0, new_len = 1, tmp, ans = 0;
struct node_idx *ptr = nodes, *new_ptr = new, *tmp_ptr;
while (new_len) {
tmp_ptr = new_ptr;
new_ptr = ptr;
ptr = tmp_ptr;
len = new_len;
new_len = 0;
for (int i = 0; i < len; i++) {
if (ptr[i].node->left) {
new_ptr[new_len].idx = new_len;
new_ptr[new_len++].node = ptr[i].node->left;
}
if (ptr[i].node->right) {
new_ptr[new_len].idx = new_len;
new_ptr[new_len++].node = ptr[i].node->right;
}
}
qsort(ptr, len, sizeof(struct node_idx), cmp);
for (int i = 0; i < len; i++)
while (ptr[i].idx != i) {
ans++;
tmp = ptr[i].idx;
ptr[i].idx = ptr[ptr[i].idx].idx;
ptr[tmp].idx = tmp;
}
}
return ans;
}
int main() {
struct TreeNode *r1 = treenode_create(1);
r1->left = treenode_create(4);
r1->left->left = treenode_create(7);
r1->left->right = treenode_create(6);
r1->right = treenode_create(3);
r1->right->left = treenode_create(8);
r1->right->right = treenode_create(5);
r1->right->left->left = treenode_create(9);
r1->right->right->left = treenode_create(10);
struct TreeNode *r2 = treenode_create(1);
r2->left = treenode_create(3);
r2->left->left = treenode_create(7);
r2->left->right = treenode_create(6);
r2->right = treenode_create(2);
r2->right->left = treenode_create(5);
r2->right->right = treenode_create(4);
struct TreeNode *r3 = treenode_create(1);
r3->left = treenode_create(2);
r3->left->left = treenode_create(4);
r3->left->right = treenode_create(5);
r3->right = treenode_create(3);
r3->right->left = treenode_create(6);
printf("%d\n", minimumOperations(r1)); // expect: 3
printf("%d\n", minimumOperations(r2)); // expect: 3
printf("%d\n", minimumOperations(r3)); // expect: 0
treenode_free(r1);
treenode_free(r2);
treenode_free(r3);
}
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