House Robber

Easy

Python

def rob(nums):
    a,b=0,0
    for n in nums: a,b=b,max(b,a+n)
    return b

Java

public int rob(int[] nums){
    int a=0,b=0;
    for(int n:nums){int t=Math.max(b,a+n);a=b;b=t;}
    return b;
}

Space-optimized. Simultaneous swap vs temp.

Python

def rob(nums):
    a,b=0,0
    for n in nums: a,b=b,max(b,a+n)
    return b

Java

public int rob(int[] nums){
    int a=0,b=0;
    for(int n:nums){int t=Math.max(b,a+n);a=b;b=t;}
    return b;
}

1. Track two previous values
2. Rob current or skip