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hello-algo/codes/c/chapter_backtracking/preorder_traversal_ii_compa...

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/**
* File: preorder_traversal_ii_compact.c
* Created Time: 2023-05-28
* Author: Gonglja (glj0@outlook.com)
*/
#include "../utils/common.h"
// 假设路径和结果长度不超过 100
#define MAX_SIZE 100
#define MAX_RES_SIZE 100
TreeNode *path[MAX_SIZE];
TreeNode *res[MAX_RES_SIZE][MAX_SIZE];
int pathSize = 0, resSize = 0;
/* 前序遍历:例题二 */
void preOrder(TreeNode *root) {
if (root == NULL) {
return;
}
// 尝试
path[pathSize++] = root;
if (root->val == 7) {
// 记录解
for (int i = 0; i < pathSize; ++i) {
res[resSize][i] = path[i];
}
resSize++;
}
preOrder(root->left);
preOrder(root->right);
// 回退
pathSize--;
}
/* Driver Code */
int main() {
int arr[] = {1, 7, 3, 4, 5, 6, 7};
TreeNode *root = arrayToTree(arr, sizeof(arr) / sizeof(arr[0]));
printf("\n初始化二叉树\n");
printTree(root);
// 前序遍历
preOrder(root);
printf("\n输出所有根节点到节点 7 的路径\n");
for (int i = 0; i < resSize; ++i) {
int *vals = malloc(MAX_SIZE * sizeof(int));
int size = 0;
for (int j = 0; res[i][j] != NULL; ++j) {
vals[size++] = res[i][j]->val;
}
printArray(vals, size);
free(vals);
}
// 释放内存
freeMemoryTree(root);
return 0;
}