题解 | #二叉树的前序遍历#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param root TreeNode类 
 * @return int整型一维数组
 * @return int* returnSize 返回数组行数
 */
typedef struct TreeNode TreeNode;
int count = 0;

void PreOrder(TreeNode* root,int *p){
    if(root==NULL){
        return;;
    }
    p[count++] = root->val;
    PreOrder(root->left,p);
    PreOrder(root->right,p);
}

int* preorderTraversal(struct TreeNode* root, int* returnSize ) {
    // write code here
    int *p = (int*)malloc(sizeof(int)*100);
    PreOrder(root,p);
    *returnSize = count;
    return p;
}