diff --git a/src/main/java/com/dota/design/_382/Solution.java b/src/main/java/com/dota/design/_382/Solution.java
new file mode 100644
index 0000000..18cf13f
--- /dev/null
+++ b/src/main/java/com/dota/design/_382/Solution.java
@@ -0,0 +1,35 @@
+package com.dota.design._382;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+class ListNode {
+     int val;
+     ListNode next;
+     ListNode() {}
+     ListNode(int val) { this.val = val; }
+     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ }
+class Solution {
+    List<Integer> list ;
+    Random r;
+    public Solution(ListNode head) {
+        r = new Random();
+        list = new ArrayList<Integer>();
+        while (head != null) {
+            list.add(head.val);
+            head = head.next;
+        }
+    }
+    
+    public int getRandom() {
+        return list.get(r.nextInt(list.size()));
+    }
+}
+
+/**
+ * Your Solution object will be instantiated and called as such:
+ * Solution obj = new Solution(head);
+ * int param_1 = obj.getRandom();
+ */
\ No newline at end of file
diff --git a/src/main/java/com/dota/design/_398/Solution.java b/src/main/java/com/dota/design/_398/Solution.java
new file mode 100644
index 0000000..db7489f
--- /dev/null
+++ b/src/main/java/com/dota/design/_398/Solution.java
@@ -0,0 +1,22 @@
+package com.dota.design._398;
+
+import java.util.*;
+
+class Solution {
+
+	Map<Integer, List<Integer>> map = new HashMap<>();
+  Random r;
+	public Solution(int[] nums) {
+		r = new Random();
+		for (int i = 0; i < nums.length; i++) {
+			map.computeIfAbsent(nums[i], k -> new ArrayList<>());
+			map.get(nums[i]).add(i);
+		}
+	}
+
+	public int pick(int target) {
+		List<Integer> list = map.get(target);
+		return list.get(r.nextInt(list.size()));
+
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/design/_497/Solution.java b/src/main/java/com/dota/design/_497/Solution.java
new file mode 100644
index 0000000..af73704
--- /dev/null
+++ b/src/main/java/com/dota/design/_497/Solution.java
@@ -0,0 +1,40 @@
+package com.dota.design._497;
+
+import java.util.Random;
+
+class Solution {
+	Random rand = new Random();
+	int[][] rects;
+	int[] dp;
+
+	public Solution(int[][] rects) {
+		this.rects = rects;
+		dp = new int[rects.length];
+		dp[0] = (1 + rects[0][2] - rects[0][0]) * (1 + rects[0][3] - rects[0][1]);
+		for (int i = 1; i < rects.length; i++) {
+			dp[i] = dp[i - 1] + ((rects[i][2] - rects[i][0] + 1) * (rects[i][3] - rects[i][1] + 1));
+		}
+	}
+
+	public int[] pick() {
+		var ranInt = rand.nextInt(dp[dp.length - 1]) + 1;
+		int idx = 0;
+		int left = 0, right = rects.length - 1;
+		while(left < right) {
+			int mid = left + (right - left) / 2;
+			if (dp[mid] >= ranInt) {
+				right = mid;
+			} else left = mid+1;
+		}
+		idx = right;
+		int x = rand.nextInt(rects[idx][2] - rects[idx][0] + 1);
+		int y = rand.nextInt(rects[idx][3] - rects[idx][1] + 1);
+		return new int[]{x + rects[idx][0], y + rects[idx][1]};
+	}
+}
+
+/**
+ * Your Solution object will be instantiated and called as such:
+ * Solution obj = new Solution(rects);
+ * int[] param_1 = obj.pick();
+ */
\ No newline at end of file
diff --git a/src/main/java/com/dota/greedy/_3227/Solution.java b/src/main/java/com/dota/greedy/_3227/Solution.java
new file mode 100644
index 0000000..a38dadd
--- /dev/null
+++ b/src/main/java/com/dota/greedy/_3227/Solution.java
@@ -0,0 +1,13 @@
+package com.dota.greedy._3227;
+
+class Solution {
+    public boolean doesAliceWin(String s) {
+        int c = 0;
+        for (int i = 0; i < s.length(); i++) {
+            if ("aeiou".indexOf(s.charAt(i)) != -1) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/math/_2614/Solution.java b/src/main/java/com/dota/math/_2614/Solution.java
new file mode 100644
index 0000000..816628a
--- /dev/null
+++ b/src/main/java/com/dota/math/_2614/Solution.java
@@ -0,0 +1,31 @@
+package com.dota.math._2614;
+
+class Solution {
+    public int diagonalPrime(int[][] nums) {
+        int max = 0;
+        int n = nums.length;
+        for (int i = 0; i < nums.length; i++) {
+            if (isSu(nums[i][n-1-i])) {
+                max = Math.max(max, nums[i][n-1-i]);
+            }
+
+            if (isSu(nums[i][i])) {
+                max = Math.max(max, nums[i][i]);
+            }
+        }
+        return max;
+    }
+
+    boolean isSu(int num) {
+        if (num == 1) {
+            return false;
+        }
+        for (int i=2;i*i<=num;i++) {
+            if (num % i == 0) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/str/_3110/Solution.java b/src/main/java/com/dota/str/_3110/Solution.java
new file mode 100644
index 0000000..80b8127
--- /dev/null
+++ b/src/main/java/com/dota/str/_3110/Solution.java
@@ -0,0 +1,12 @@
+package com.dota.str._3110;
+
+class Solution {
+    public int scoreOfString(String s) {
+        int n = s.length();
+        int res = 0;
+        for (int i = 1; i < n; i++) {
+            res += Math.abs(s.charAt(i) - s.charAt(i - 1));
+        }
+        return res;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/str/_3340/Solution.java b/src/main/java/com/dota/str/_3340/Solution.java
new file mode 100644
index 0000000..9351feb
--- /dev/null
+++ b/src/main/java/com/dota/str/_3340/Solution.java
@@ -0,0 +1,13 @@
+package com.dota.str._3340;
+
+class Solution {
+	public boolean isBalanced(String num) {
+		int res = 0;
+		boolean flag = true;
+		for (char c : num.toCharArray()) {
+			res = flag ? res + (c - '0') : res - (c - '0');
+			flag = !flag;
+		}
+		return res == 0;
+	}
+}
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