Merge remote-tracking branch 'upstream/master'

1 files changed, 49 insertions, 0 deletions

diff --git a/challenge-113/stuart-little/node/ch-2.js b/challenge-113/stuart-little/node/ch-2.js
new file mode 100755
index 0000000000..2364b0a3a8
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+++ b/challenge-113/stuart-little/node/ch-2.js
@@ -0,0 +1,49 @@
+#!/usr/bin/env node
+
+const printTree = require('print-tree');
+
+function split2trees(lst) {    
+    ix = [...lst.keys()].find(i => 2*lst.slice(0,i+1).filter(x => x === ".").length > i+1 );
+    return [lst.slice(0,ix+1), lst.slice(ix+1)]
+}
+
+function mkTree(lst) {
+    if (lst[0] === ".") {
+	return { name: "" };
+    };
+    const nm = lst[0];
+    const [lft,rght] = split2trees(lst.slice(1));
+    return {
+	name: nm,
+	children: [mkTree(lft),mkTree(rght)],
+    };
+}
+
+const inTreeList = (process.argv.length > 2) ? (process.argv.slice(2)) : (["1", "2", "4", ".", "7", ".", ".", ".", "3", "5", ".", ".", "6", ".", "."]);
+const sm = inTreeList.reduce((acc,el) => {return acc + (parseInt(el) || 0)}, 0);
+const outTreeList = inTreeList.map(x => (parseInt(x)) ? (sm - parseInt(x)) : x);
+
+printTree(
+    mkTree(outTreeList),
+    node => node.name.toString(),
+    node => node.children,
+);
+
+/*
+run <script> <tree in preorder form with '.' for empty nodes, entered as space-separated values>
+
+ref: https://stackoverflow.com/a/2676849/11064961
+
+e.g. 1 2 4 . 7 . . . 3 5 . . 6 . . represents the tree
+
+        1
+       / \
+      2   3
+     /   / \
+    4   5   6
+     \
+      7
+
+given as an example in the problem formulation at https://perlweeklychallenge.org/blog/perl-weekly-challenge-113/#TASK2
+*/
+