C语言 | Leetcode C语言题解之第515题在每个树行中找最大值

题目：

题解：

#define MAX_NODE_SIZE 10001
#define MAX(a, b) ((a) > (b) ? (a) : (b))

int* largestValues(struct TreeNode* root, int* returnSize) {
    if (!root) {
        *returnSize = 0;
        return NULL;
    }
    int *res = (int *)malloc(sizeof(int) * MAX_NODE_SIZE);
    int pos = 0;
    struct TreeNode **queue = (struct TreeNode *)malloc(sizeof(struct TreeNode *) * MAX_NODE_SIZE);
    int head = 0, tail = 0;
    queue[tail++] = root;
    while (head != tail) {
        int len = tail - head;
        int maxVal = INT_MIN;
        while (len > 0) {
            len--;
            struct TreeNode *node = queue[head++];
            maxVal = MAX(maxVal, node->val);
            if (node->left) {
                queue[tail++] = node->left;
            }
            if (node->right) {
                queue[tail++] = node->right;
            }
        }
        res[pos++] = maxVal;
    }
    *returnSize = pos;
    free(queue);
    return res;
}