Add week 10 solutions: houseRobber1, 2

Author: yolophg

house-robber-ii/yolophg.js

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+// Time Complexity: O(n)
+// Space Complexity: O(n)
+
+var rob = function (nums) {
+  // to rob a linear list of houses
+  function robLinear(houses) {
+    let prev1 = 0;
+    let prev2 = 0;
+
+    for (let money of houses) {
+      let temp = Math.max(prev1, money + prev2);
+      prev2 = prev1;
+      prev1 = temp;
+    }
+
+    return prev1;
+  }
+
+  // 1. excluding the last house (rob from first to second-to-last)
+  // 2. excluding the first house (rob from second to last)
+  let robFirstToSecondLast = robLinear(nums.slice(0, -1));
+  let robSecondToLast = robLinear(nums.slice(1));
+
+  // return the maximum money
+  return Math.max(robFirstToSecondLast, robSecondToLast);
+};

house-robber/yolophg.js

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+// Time Complexity: O(n)
+// Space Complexity: O(n)
+
+var rob = function (nums) {
+  // to store the maximum money that can be robbed up to each house
+  let memo = new Array(nums.length).fill(-1);
+
+  function robFrom(i) {
+    // if the index is out of bounds, return 0
+    if (i >= nums.length) return 0;
+
+    // 1. rob this house and move to the house two steps ahead
+    // 2. skip this house and move to the next house
+    // take the maximum of these two choices
+    let result = Math.max(nums[i] + robFrom(i + 2), robFrom(i + 1));
+
+    // store the result
+    memo[i] = result;
+
+    return result;
+  }
+
+  // start robbing from the first house
+  return robFrom(0);
+};