treeNodeInColumn.js

// Print the nodes of binary tree column wise
/*

Input:

       8
     /   \
    6     10
   / \   /  \
  4   7 9    12
 / \
3   5


Output:
3
4
6 5
8 7 9
10
12

*/

function insertInColumns(root, index, hash, min, max) {
    if (!root) {
        return {
            min: min,
            max: max
        };
    }

    hash[index] = hash[index] || [];
    hash[index].push(root.value);    

    var leftResult = insertInColumns(root.left, index-1, hash, min, max);
    var rightResult = insertInColumns(root.right, index+1, hash, min, max);

    return {
        min: Math.min(index, Math.min(leftResult.min, rightResult.min)),
        max: Math.max(index, Math.max(leftResult.max, rightResult.max))
    };
}

var tree = {
    value: 8,    
    left: {
        value: 6,
        left: {
            value: 4,
            left: {
                value: 3
            },
            right: {
                value: 5
            }
        },
        right: {
            value: 7
        }
    },
    right: {
        value: 10,
        left: {
            value: 9
        },
        right: {
            value: 12
        }
    }
};

var hash = {};
var result = insertInColumns(tree, 0, hash, 0, 0);

var output = "";

for (var i = result.min; i <= result.max; i++) {
    var values = hash[i];

    if (!values) {
        continue;
    }

    var str = "";
    for (var j = 0; j < values.length; j++) {
        str += ((j > 0) ? " " : "") + values[j];
    }
    output += str + ((i < result.max) ? "\n" : "");
}

console.log(output);