isMeasureable

isMeasureable.js

//Increase the list by one and does carry over between digits. 
var increaseByOne = function(listOfWeights){
    var newList = listOfWeights;
    newList[newList.length-1] += 1;
    for(var i = listOfWeights.length-1; i>0; i--){
        var newWeight= listOfWeights[i];
        if(newWeight==2){
            newWeight=-1;                    
            newList[i-1]+= 1;
        }
        newList[i]=newWeight;            
    }
    if(newList[0]==2)
        newList[0]=-1;
    return newList;
};

//Testing to see if two arrays are equal. 
var equalArraysTest = function(a,b){
    if(a.length != b.length)
        return false;
    for(var i = 0; i<a.length; i++){
        if(a[i] != b[i]){
            return false;
        }
    }
    return true;
};
// Takes in a target and a set of weights and goes through to check if any possible combination works. 
var isMeasureable = function(target, weights){
    var testEqual = function(secondWeights){
        var sum = 0;
        for(var i = 0; i < weights.length; i++ ){
            sum += weights[i]*secondWeights[i];

        }
        return target==sum;
    };
    //Simple test case
    if(target ==0){
        return true;
    }
    
    //Set up weighting to be a list of -1's. 
    var weighting = new Array(weights.length);
    var startingOut= new Array(weights.length);
    for(var j = 0; j< weights.length; j++){
        weighting[j]= -1;
        startingOut[j] =-1;
    }

    //While loop boolean
    var finished = false;
    var possible = false;

    //While loop to do the testing and check whether we are done yet.
    while(!finished){
        if(testEqual(weighting)){
            possible=true;
        }
        weighting= increaseByOne(weighting);
        if(equalArraysTest(startingOut,weighting) || possible){
            finished=true;
        }
    }
    return possible;
};