Add C++ Solution

Author: jinshendan

Problems/.DS_Store

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    int solve(int k, int n, vector<int>& dp)
+    {
+        if (k == 1) return n;
+        if (dp[n] != 0) return dp[n];
+        for (int i = 1; i <= n; i++)
+        {
+            int tmp = 1 + max(solve(k-1, i-1, dp), solve(k, n-i, dp));
+            if (dp[n] == 0) dp[n] = tmp;
+            else dp[n] = min(dp[n], tmp);
+        }
+        return dp[n];
+    }
+
+    int twoEggDrop(int n) {
+        vector<int> dp(n+1, 0);
+        return solve(2, n, dp);
+    }
+};

Problems/28-Egg-Drop-With-2-Eggs-and-N-Floors/Egg-Drop-With-2-Eggs-and-N-Floors.cpp

@@ -0,0 +1,23 @@
+class Solution {
+public:
+    int numSplits(string s) {
+        int n = s.length();
+        vector<int> right(n+1, 0);
+        
+        unordered_set<char> ss;
+        for (int i = n-1; i >= 0; i--)
+        {
+            ss.insert(s[i]);
+            right[i] = ss.size();
+        }
+
+        ss.clear();
+        int ans = 0;
+        for (int i = 0; i < n; i++)
+        {
+            ss.insert(s[i]);
+            if (ss.size() == right[i+1]) ans++;
+        }
+        return ans;
+    }
+};

Problems/29-Number-of-Good-Ways-to-Split-a-String/Number-of-Good-Ways-to-Split-a-String.cpp

@@ -0,0 +1,29 @@
+class Solution {
+public:
+    int minSideJumps(vector<int>& obstacles) {
+        int n = obstacles.size();
+        vector<vector<int>> dp(n, vector<int>(3,0));
+        dp[0][0] = dp[0][2] = 1;
+       
+        for (int i = 1; i < n; i++)
+        {
+            for (int j = 0; j < 3; j++)
+            {
+                dp[i][j] = INT_MAX-1;
+                if (obstacles[i] - 1 == j) continue;
+                
+                if (obstacles[i-1] -1 != j) dp[i][j] = min(dp[i][j], dp[i-1][j]);
+
+                int lane = (j+1) % 3;
+                if (obstacles[i-1] -1 != lane && obstacles[i] -1 != lane) dp[i][j] = min(dp[i][j], dp[i-1][lane]+1);
+
+                lane = (j+2) % 3;
+                if (obstacles[i-1] -1 != lane && obstacles[i] -1 != lane) dp[i][j] = min(dp[i][j], dp[i-1][lane]+1);
+            }
+        }
+
+        int ans = INT_MAX;
+        for (int j = 0; j < 3; j++) ans = min(ans, dp[n-1][j]);
+        return ans;
+    }
+};

Problems/30-Minimum-Sideway-Jumps/Minimum-Sideway-Jumps.cpp

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    int deleteAndEarn(vector<int>& nums) {
+        unordered_map<int, int> m;
+        for (auto x: nums) m[x]++;
+
+        vector<int> dp(10001, 0); 
+        dp[1] = m[1];
+        for (int i = 2; i <= 10000; i++)
+        {
+            dp[i] = max(dp[i-2] + i * m[i], dp[i-1]);
+        }
+        return dp[10000];
+    }
+};

Problems/31-Delete-and-Earn/Delete-and-Earn.cpp

@@ -33,6 +33,10 @@ Solutions in various programming languages are provided. Enjoy it.
 25. 2023/02/16 [#926 Flip String to Monotone Increasing](https://github.com/LeetcodeRush/Leetcode/tree/main/Problems/25-Flip-String-to-Monotone-Increasing): DP
 26. 2023/02/17 [#935 Knight Dialer](https://github.com/LeetcodeRush/Leetcode/tree/main/Problems/26-Knight-Dialer): DP
 27. 2023/02/18 [#1664 Ways to Make a Fair Array](https://github.com/LeetcodeRush/Leetcode/tree/main/Problems/27-Ways-to-Make-a-Fair-Array): DP
+28. 2023/02/19 [#1884 Egg Drop With 2 Eggs and N Floors](): DP
+29. 2023/02/20 [#1525 Number of Good Ways to Split a String](): DP
+30. 2023/02/21 [#1824 Minimum Sideway Jumps](): DP
+31. 2023/02/22 [#740 Delete and Earn](): DP
 
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