题目：

题解：

char** binaryTreePaths(struct TreeNode* root, int* returnSize) {char** paths = (char**)malloc(sizeof(char*) * 1001);*returnSize = 0;if (root == NULL) {return paths;}struct TreeNode** node_queue = (struct TreeNode**)malloc(sizeof(struct TreeNode*) * 1001);char** path_queue = (char**)malloc(sizeof(char*) * 1001);int left = 0, right = 0;char* tmp = malloc(sizeof(char) * 1001);sprintf(tmp, "%d", root->val);node_queue[right] = root;path_queue[right++] = tmp;while (left < right) {struct TreeNode* node = node_queue[left];char* path = path_queue[left++];if (node->left == NULL && node->right == NULL) {paths[(*returnSize)++] = path;} else {int n = strlen(path);if (node->left != NULL) {char* tmp = malloc(sizeof(char) * 1001);for (int i = 0; i < n; i++) {tmp[i] = path[i];}sprintf(tmp + n, "->%d", node->left->val);node_queue[right] = node->left;path_queue[right++] = tmp;}if (node->right != NULL) {char* tmp = malloc(sizeof(char) * 1001);for (int i = 0; i < n; i++) {tmp[i] = path[i];}sprintf(tmp + n, "->%d", node->right->val);node_queue[right] = node->right;path_queue[right++] = tmp;}}}return paths;
}