How to solve The Times 2 "Polygon" puzzle

solver.js

#!/usr/bin/env node

// This should solve the "Polygon" puzzle in The Times 2 "MindGames".
// Assumes a *nix system with the usual dictionary of words in the usual
// place.
// A few of the rules for what words count are a bit complicated... you could
// probably extend this with a Porter Stemmer, if you cared enough.

var fs       = require("fs"),
    readline = require("readline"),
    _        = require("underscore"),
    WORDS    = fs.readFileSync("/usr/share/dict/words").toString().split("\n");

var Solver = function() {
    var inputs = [],
        centre,
        num;

    (function trimWords() {
        WORDS = _.chain(WORDS)

        // excluding capitalised words
        .reject(function(word) {
            return /[A-Z]/.test(word[0]);
        })

        // plurals - TODO

        // conjugated words - TODO

        // adverbs ending in LY
        .reject(function(word) {
            return /ly$/.test(word);
        })

        // comparatives and superlatives - TODO

        .value();
    })();

    var solve = function() {
        var last = _.last(inputs, 2);
        centre   = last[0];
        num      = parseInt(last[1], 10);

        console.log("Letters:\n", _.first(inputs, inputs.length - 1).join(","));
        console.log("Must contain:\n", centre);

        WORDS = _.chain(WORDS)
        // must contain the centre
        .reject(function(word) {
            return word.indexOf(centre) < 0;
        })
        // must not be longer than the words in the polygon
        .reject(function(word) {
            return word.length > inputs.length;
        })
        // and must not be less than `num` letters
        .reject(function(word) {
            return word.length < num;
        })
        .value();

        WORDS = _.select(WORDS, function(word) {
            var len     = word.length,
                _inputs = inputs,
                match   = 0,
                i       = 0,
                l,
                idx;

            for (; i < len; ++i) {
                l = word[i];

                if ((idx = _inputs.indexOf(l)) > -1) {
                    ++match;
                    var arr = _inputs;
                    _inputs = (arr.slice(0, idx) + arr.slice(idx + 1));
                } else {
                    break;
                }
            }

            return match === len;
        });

        var result = WORDS.sort(function(a,b) {
            return b.length - a.length;
        });

        console.log("\nLongest:\n", result.shift());
        console.log("\nThe rest:\n", result.sort().join(", "));
    };

    return {
        add : function(line) {
            inputs.push(line[0]);
        },
        solve : solve
    }
};

console.log("Enter the letters, pressing return after each one.");
console.log("Enter the letter in the middle of the polygon last.");
console.log("Finish with the *minimum length* of word required (usually three or four).");

var solver = new Solver();

var rl = readline.createInterface({
    input    : process.stdin,
    output   : process.stdout,
    terminal : false
})
.on("line", function(line) {
    !line.length ? rl.close() : solver.add(line);
})
.on("close", solver.solve);