golang 解法, 执行用时: 0 ms, 内存消耗: 2.6 MB, 提交时间: 2023-06-13 10:00:47

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
type data struct{ col, row, val int }

func verticalTraversal(root *TreeNode) (ans [][]int) {
    nodes := []data{}
    var dfs func(*TreeNode, int, int)
    dfs = func(node *TreeNode, row, col int) {
        if node == nil {
            return
        }
        nodes = append(nodes, data{col, row, node.Val})
        dfs(node.Left, row+1, col-1)
        dfs(node.Right, row+1, col+1)
    }
    dfs(root, 0, 0)

    sort.Slice(nodes, func(i, j int) bool {
        a, b := nodes[i], nodes[j]
        return a.col < b.col || a.col == b.col && (a.row < b.row || a.row == b.row && a.val < b.val)
    })

    lastCol := math.MinInt32
    for _, node := range nodes {
        if node.col != lastCol {
            lastCol = node.col
            ans = append(ans, nil)
        }
        ans[len(ans)-1] = append(ans[len(ans)-1], node.val)
    }
    return
}

python3 解法, 执行用时: 52 ms, 内存消耗: 16.3 MB, 提交时间: 2023-06-13 10:00:26

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def verticalTraversal(self, root: TreeNode) -> List[List[int]]:
        nodes = list()

        def dfs(node: TreeNode, row: int, col: int) -> None:
            if not node:
                return

            nodes.append((col, row, node.val))
            dfs(node.left, row + 1, col - 1)
            dfs(node.right, row + 1, col + 1)

        dfs(root, 0, 0)
        nodes.sort()
        ans, lastcol = list(), float("-inf")

        for col, row, value in nodes:
            if col != lastcol:
                lastcol = col
                ans.append(list())
            ans[-1].append(value)
        
        return ans

java 解法, 执行用时: 3 ms, 内存消耗: 40.5 MB, 提交时间: 2023-06-13 09:59:55

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
// dfs + 哈希表 + 排序
class Solution {
    Map<TreeNode, int[]> map = new HashMap<>(); // col, row, val
    public List<List<Integer>> verticalTraversal(TreeNode root) {
        map.put(root, new int[]{0, 0, root.val});
        dfs(root);
        List<int[]> list = new ArrayList<>(map.values());
        Collections.sort(list, (a, b)->{
            if (a[0] != b[0]) return a[0] - b[0];
            if (a[1] != b[1]) return a[1] - b[1];
            return a[2] - b[2];
        });
        int n = list.size();
        List<List<Integer>> ans = new ArrayList<>();
        for (int i = 0; i < n; ) {
            int j = i;
            List<Integer> tmp = new ArrayList<>();
            while (j < n && list.get(j)[0] == list.get(i)[0]) tmp.add(list.get(j++)[2]);
            ans.add(tmp);
            i = j;
        }
        return ans;
    }
    void dfs(TreeNode root) {
        if (root == null) return ;
        int[] info = map.get(root);
        int col = info[0], row = info[1], val = info[2];
        if (root.left != null) {
            map.put(root.left, new int[]{col - 1, row + 1, root.left.val});
            dfs(root.left);
        }
        if (root.right != null) {
            map.put(root.right, new int[]{col + 1, row + 1, root.right.val});
            dfs(root.right);
        }
    }
}

javascript 解法, 执行用时: 72 ms, 内存消耗: 43.1 MB, 提交时间: 2023-06-13 09:59:05

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[][]}
 */
var verticalTraversal = function(root) {
    let res=[];
    const stack = []
    //前序遍历（迭代）
    if(root) stack.push([root,0,0])
    while (stack.length) {
        const n = stack.pop()
        let node=n[0];
        let row=n[1];
        let col=n[2];
        res.push([node.val,row,col]);
        if(node.right) stack.push([node.right,row+1,col+1])
        if(node.left) stack.push([node.left,row+1,col-1])
    }
    //排序
    res.sort((v1,v2)=>v1[2]-v2[2]||v1[1]-v2[1]||v1[0]-v2[0])
    //合并
    let result=[[res[0][0]]];
    for(let i=1;i<res.length;i++){
        if(res[i][2]!==res[i-1][2]){
            result.push([res[i][0]]);
        }else{
            result[result.length-1].push(res[i][0])
        }
    }
    return result
};