Javascript House Robber

house-robber.js

var home_values = [10, 20, 30, 40, 50];
//var home_values = [10,5,2,12];
var home_count = home_values.length;

function rob_recursive(count, nums) {
    //base case
    if(count === 0) return 0;
    if(count === 1) return nums[0];
    if(count === 2) return Math.max(nums[0], nums[1]);
    var maxValue = 0;
    maxValue = Math.max(maxValue, rob_recursive(count - 1, nums));
    //Next we run the second recursive call. case for when we do steal house "i"
    for(var i = count - 2; i >= 0; i--) {
        //note nums[count - 1] is the value of the last index or house "i"
        maxValue = Math.max(maxValue, rob_recursive(i, nums) + nums[count - 1] );
    }

    return maxValue;
}

var maxValue = rob_recursive(home_count, home_values);
console.log("Recursive Solution: " + maxValue);

function rob_dp(count, nums) {
    //base cases. So this to prevent loop from ever firing if count is <= 2
    if(count === 0) return 0;
    if(count === 1) return nums[0];
    if(count === 2) return Math.max(nums[0], nums[1]);
    
    //define an array F to hold max returns. this will be out table
    var F = [];
    F[0] = nums[0];
    F[1] = Math.max(nums[0], nums[1]);
    var length = nums.length;
    for(var i = 2; i < length; i++) {
        F[i] = Math.max(nums[i] + F[i - 2], F[i - 1]);
    }
    //return the last index
    return F[count - 1];
}

var maxValue = rob_dp(home_count, home_values);
console.log("Dynamic Programming Solution: " + maxValue);

/*
Bonus: this final method makes it easier to understand. Do take a look at it
This is neither recursive or DP.
*/
function rob(n, num) {
    var prevEvenMax = 0;
    var prevOddMax = 0;
    
    for (var i = 0; i < n; i++) {
        if (i % 2 === 0) {
            prevEvenMax = Math.max(prevEvenMax + num[i], prevOddMax);
        }
        else {
            prevOddMax = Math.max(prevEvenMax, prevOddMax + num[i]);
        }
    }
    
    return Math.max(prevEvenMax, prevOddMax);
}

var otherSolution = rob(home_count, home_values);
console.log("Other Solution: " + otherSolution);