update 213 java, progress

yennanliu · May 19, 2024 · 52775c7 · 52775c7
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diff --git a/README.md b/README.md
@@ -1022,7 +1022,7 @@
 123| [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/)| [Python](./leetcode_python/Dynamic_Programming/best-time-to-buy-and-sell-stock-iii.py)   | _O(m * n)_      | _O(n)_ | Hard |`amazon`, uber, apple| AGAIN* (not start) (1)
 152| [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/)|[Python](./leetcode_python/Dynamic_Programming/maximum-product-subarray.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/MaximumProductSubarray.java)| _O(n)_ | _O(1)_ | Medium |dp, brute force, Curated Top 75, google, amazon, linkedin| AGAIN***** (1)
 198| [House Robber](https://leetcode.com/problems/house-robber/)| [Python](./leetcode_python/Dynamic_Programming/house-robber.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/HouseRobber.java) | _O(n)_ | _O(1)_ | Easy|Curated Top 75, dp basic,`amazon`| AGAIN*** (2)
-213| [House Robber II](https://leetcode.com/problems/house-robber-ii/)| [Python](./leetcode_python/Dynamic_Programming/house-robber-ii.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/HouseRobber2.java) | _O(n)_| _O(1)_| Medium|brute force, recursion, dp, Curated Top 75, google, amazon| AGAIN (2)
+213| [House Robber II](https://leetcode.com/problems/house-robber-ii/)| [Python](./leetcode_python/Dynamic_Programming/house-robber-ii.py), [Java](./leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/HouseRobber2.java) | _O(n)_| _O(1)_| Medium|brute force, recursion, dp, Curated Top 75, google, amazon| OK**** (3) (but again)
 221| [Maximal Square](https://leetcode.com/problems/maximal-square/)|[Python](./leetcode_python/Dynamic_Programming/maximal-square.py) | _O(n^2)_   | _O(n)_ | Medium | EPI, dp, `amazon`,`fb` | AGAIN** (3) (not start)
 256| [Paint House](https://leetcode.com/problems/paint-house/) | [Python](./leetcode_python/Dynamic_Programming/paint-house.py) | _O(n)_| _O(1)_| Medium |🔒| AGAIN (not start) 
 276| [Paint Fence](https://leetcode.com/problems/paint-fence/) | [Python](./leetcode_python/Dynamic_Programming/paint-fence.py) | _O(n)_| _O(1)_| Easy |🔒| AGAIN 

diff --git a/data/progress.txt b/data/progress.txt
@@ -1,4 +1,4 @@
-20240519: 207,79,206,213(todo),198
+20240519: 207,79,206,213,198
 20240518: 212(todo),211,338,208(again)
 20240517: 347,253(todo),91(todo),217
 20240516: 226,98,253(todo)

diff --git a/data/to_review.txt b/data/to_review.txt
@@ -1,4 +1,4 @@
-2024-07-13 -> ['207,79,206,213(todo),198']
+2024-07-13 -> ['207,79,206,213,198']
 2024-07-12 -> ['212(todo),211,338,208(again)']
 2024-07-11 -> ['347,253(todo),91(todo),217']
 2024-07-10 -> ['226,98,253(todo)']
@@ -8,7 +8,7 @@
 2024-07-06 -> ['371']
 2024-07-05 -> ['121,252']
 2024-07-04 -> ['125']
-2024-06-22 -> ['207,79,206,213(todo),198']
+2024-06-22 -> ['207,79,206,213,198']
 2024-06-21 -> ['212(todo),211,338,208(again)']
 2024-06-20 -> ['347,253(todo),91(todo),217']
 2024-06-19 -> ['226,98,253(todo)']
@@ -18,27 +18,27 @@
 2024-06-15 -> ['371']
 2024-06-14 -> ['121,252']
 2024-06-13 -> ['125']
-2024-06-09 -> ['207,79,206,213(todo),198']
+2024-06-09 -> ['207,79,206,213,198']
 2024-06-08 -> ['212(todo),211,338,208(again)']
 2024-06-07 -> ['347,253(todo),91(todo),217']
 2024-06-06 -> ['226,98,253(todo)']
 2024-06-05 -> ['104,230,102,100']
 2024-06-04 -> ['105,106']
 2024-06-03 -> ['242,235']
 2024-06-02 -> ['371']
-2024-06-01 -> ['207,79,206,213(todo),198', '121,252']
+2024-06-01 -> ['207,79,206,213,198', '121,252']
 2024-05-31 -> ['212(todo),211,338,208(again)', '125']
 2024-05-30 -> ['347,253(todo),91(todo),217']
 2024-05-29 -> ['226,98,253(todo)']
 2024-05-28 -> ['104,230,102,100']
-2024-05-27 -> ['207,79,206,213(todo),198', '105,106']
+2024-05-27 -> ['207,79,206,213,198', '105,106']
 2024-05-26 -> ['212(todo),211,338,208(again)', '242,235']
 2024-05-25 -> ['347,253(todo),91(todo),217', '371']
-2024-05-24 -> ['207,79,206,213(todo),198', '226,98,253(todo)', '121,252']
+2024-05-24 -> ['207,79,206,213,198', '226,98,253(todo)', '121,252']
 2024-05-23 -> ['212(todo),211,338,208(again)', '104,230,102,100', '125']
-2024-05-22 -> ['207,79,206,213(todo),198', '347,253(todo),91(todo),217', '105,106']
-2024-05-21 -> ['207,79,206,213(todo),198', '212(todo),211,338,208(again)', '226,98,253(todo)', '242,235']
-2024-05-20 -> ['207,79,206,213(todo),198', '212(todo),211,338,208(again)', '347,253(todo),91(todo),217', '104,230,102,100', '371']
+2024-05-22 -> ['207,79,206,213,198', '347,253(todo),91(todo),217', '105,106']
+2024-05-21 -> ['207,79,206,213,198', '212(todo),211,338,208(again)', '226,98,253(todo)', '242,235']
+2024-05-20 -> ['207,79,206,213,198', '212(todo),211,338,208(again)', '347,253(todo),91(todo),217', '104,230,102,100', '371']
 2024-05-19 -> ['212(todo),211,338,208(again)', '347,253(todo),91(todo),217', '226,98,253(todo)', '105,106', '121,252']
 2024-05-18 -> ['347,253(todo),91(todo),217', '226,98,253(todo)', '104,230,102,100', '242,235', '125']
 2024-05-17 -> ['226,98,253(todo)', '104,230,102,100', '105,106', '371']

diff --git a/leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/HouseRobber2.java b/leetcode_java/src/main/java/LeetCodeJava/DynamicProgramming/HouseRobber2.java
@@ -19,11 +19,15 @@ public int rob(int[] nums) {
             return Math.max(nums[0], nums[1]);
         }
 
-        // Consider the scenario where the first and last houses are adjacent
+        // Consider the scenario where the first and last houses are adjacent (nums is a "circular" array)
         // so either
-        //  -> we rob first and last 2 idx
-        //  -> or rob 2nd and last idx
+        //
+        //  -> case 1) we rob first and last 2 idx (e.g. 0 idx, and k-2 idx)
+        //  -> case 2) or rob 2nd and last idx (e.g. 1 idx, and k-1 idx)
+
+        // case 1)
         int max1 = robRange(nums, 0, nums.length - 2);
+        // case 2)
         int max2 = robRange(nums, 1, nums.length - 1);
 
         return Math.max(max1, max2);
@@ -32,11 +36,13 @@ public int rob(int[] nums) {
     // NOTE !!! define robRange(int[] nums, int start, int end)
     // with start, end idx
     public int robRange(int[] nums, int start, int end) {
+
         int[] dp = new int[nums.length];
         dp[start] = nums[start];
         dp[start + 1] = Math.max(nums[start], nums[start + 1]);
 
         for (int i = start + 2; i <= end; i++) {
+            // still the same dp logic as LC 198
             dp[i] = Math.max(dp[i - 1], dp[i - 2] + nums[i]);
         }
 

diff --git a/leetcode_java/src/main/java/dev/workspace3.java b/leetcode_java/src/main/java/dev/workspace3.java
@@ -1022,4 +1022,67 @@ public int rob_(int[] nums) {
         return dp[nums.length-1];
     }
 
+    // LC 213
+    public int rob_2(int[] nums) {
+
+        if (nums.length <= 3){
+
+            if (nums.length == 0){
+                return 0;
+            }
+
+            if (nums.length == 1){
+                return nums[0];
+            }
+
+            if (nums.length == 2){
+                return Math.max(nums[0], nums[1]);
+            }
+
+            return Math.max(nums[0]+nums[2], nums[1]);
+        }
+
+        int[] dp = new int[nums.length];
+
+        dp[0] = nums[0];
+        dp[1] = Math.max(nums[0], nums[1]);
+
+        /**
+         *
+         *  // 1, 2, 3, ... k-2, k-1, k
+         *  // case 1) take dp[1]
+         *
+         *   dp[k] = max(dp(k-2), dp(k-1))
+         *
+         *  // case 2) NOT take dp[1]
+         *
+         *   dp[0] = 0
+         *   dp[1] = nums[1]
+         *   dp[k] = max(dp(k-2) + nums[k], dp(k-1))
+         *
+         *
+         *  nums = [1,2,3,1]
+         *
+         *  case 1)
+         *   dp[0] = 1
+         *   dp[1] = 2
+         *   dp[2] = 4
+         *   dp[3] =
+         *    max(dp(k-2), dp(k-1))  = 4
+         *     or
+         *    max(dp(k-2) + k, dp(k-1)) = 3
+         *
+         */
+
+        for (int i = 2; i < nums.length; i++){
+            dp[i] = Math.max(dp[i-2] + nums[i], dp[i-1]);
+        }
+
+        System.out.println("dp = " + dp.toString());
+        for (int x : dp){
+            System.out.println(x);
+        }
+        return dp[nums.length-1];
+    }
+
 }