doukaku13_1.js

"use strict";

function solve(input) {
    var target = parseInt(input);
    var cache = [];
    var step  = 1;
    var queue = [0, -1];
    var i     = 0;

    while(true) {
        var n = queue[i];
        i++;
        if(n === -1) {
            step += 1;
            queue.push(-1);
        } else {
            var n1 = n + 1;
            var n2 = n - 1;
            var n3 = n * 2;
            if(n1 === target || n2 === target || n3 === target) {
                return step.toString();
            }

            if(cache[n1] === undefined) {
                cache[n1] = true;
                queue.push(n1);
            }
            if(cache[n2] === undefined && 0 < n2) {
                cache[n2] = true;
                queue.push(n2);
            }
            if(cache[n3] === undefined) {
                cache[n3] = true;
                queue.push(n3);
            }
        }
    }
}

function test(input, expected) {
    var result = solve(input);
    if(result !== expected) {
        console.log("-------------\ninput = %s\n\nexpected = %s\nresult   = %s", input, expected, result);
    }
}

test( "59"    , "9" );
test( "10"    , "5" );
test( "11"    , "6" );
test( "12"    , "5" );
test( "13"    , "6" );
test( "14"    , "6" );
test( "15"    , "6" );
test( "16"    , "5" );
test( "17"    , "6" );
test( "18"    , "6" );
test( "27"    , "8" );
test( "28"    , "7" );
test( "29"    , "8" );
test( "30"    , "7" );
test( "31"    , "7" );
test( "32"    , "6" );
test( "33"    , "7" );
test( "34"    , "7" );
test( "35"    , "8" );
test( "41"    , "8" );
test( "71"    , "9" );
test( "1023"  , "12" );
test( "1024"  , "11" );
test( "1025"  , "12" );
test( "1707"  , "17" );
test( "683"   , "15" );
test( "123"   , "10" );
test( "187"   , "11" );
test( "237"   , "12" );
test( "5267"  , "18" );
test( "6737"  , "18" );
test( "14796" , "20" );
test( "18998" , "20" );
test( "23820" , "20" );
test( "30380" , "21" );
test( "31119" , "21" );
test( "33301" , "20" );
test( "33967" , "21" );
test( "35443" , "22" );
test( "35641" , "22" );
test( "43695" , "23" );
test( "44395" , "23" );
test( "44666" , "22" );
test( "987"   , "14" );
test( "1021"  , "13" );
test( "1019"  , "13" );
test( "1015"  , "13" );
test( "1007"  , "13" );
test( "1011"  , "14" );
test( "1003"  , "14" );
test( "983"   , "14" );
test( "999"   , "14" );
test( "2731"  , "18" );
test( "6827"  , "20" );
test( "10923" , "21" );
test( "27307" , "23" );
test( "43691" , "24" );
test( "109227", "26" );
test( "174763", "27" );