diff --git a/leetcode_py/1944.py b/leetcode_py/1944.py
new file mode 100644
index 0000000..8217e3d
--- /dev/null
+++ b/leetcode_py/1944.py
@@ -0,0 +1,25 @@
+from typing import List
+
+
+# use monotonic stack
+class Solution:
+    def canSeePersonsCount(self, heights: List[int]) -> List[int]:
+        n = len(heights)
+        result = [0] * n
+        stack = []
+        # Process from right to left
+        for i in range(n - 1, -1, -1):
+            count = 0
+            # Pop elements shorter than current height
+            while stack and heights[stack[-1]] < heights[i]:
+                count += 1
+                stack.pop()
+
+            # If stack not empty, can see one more person
+            if stack:
+                count += 1
+
+            result[i] = count
+            stack.append(i)
+
+        return result
diff --git a/leetcode_py/1998.py b/leetcode_py/1998.py
new file mode 100644
index 0000000..cee6c0e
--- /dev/null
+++ b/leetcode_py/1998.py
@@ -0,0 +1,43 @@
+from typing import List
+
+
+class Solution:
+    def gcdSort(self, nums: List[int]) -> bool:
+        # 并查集
+        def find(x):
+            if parent[x] != x:
+                parent[x] = find(parent[x])
+            return parent[x]
+
+        def union(x, y):
+            parent[find(x)] = find(y)
+
+        # 获取一个数的所有质因数
+        def get_prime_factors(n):
+            factors = set()
+            i = 2
+            while i * i <= n:
+                while n % i == 0:
+                    factors.add(i)
+                    n //= i
+                i += 1
+            if n > 1:
+                factors.add(n)
+            return factors
+
+        # 初始化并查集
+        max_num = max(nums)
+        parent = list(range(max_num + 1))
+
+        # 对每个数字，将其与其质因数连接
+        for num in nums:
+            for prime in get_prime_factors(num):
+                union(num, prime)
+
+        # 检查排序后的数组是否可以通过交换得到
+        sorted_nums = sorted(nums)
+        for i in range(len(nums)):
+            if find(nums[i]) != find(sorted_nums[i]):
+                return False
+
+        return True
diff --git a/leetcode_py/2000.py b/leetcode_py/2000.py
new file mode 100644
index 0000000..edfe30a
--- /dev/null
+++ b/leetcode_py/2000.py
@@ -0,0 +1,11 @@
+import re
+
+
+class Solution:
+    def reversePrefix(self, word: str, ch: str) -> str:
+        match = re.search(rf"{ch}", word)
+        if match:
+            position = match.start()
+            return word[: position + 1][::-1] + word[position + 1 :]
+        else:
+            return word
diff --git a/leetcode_py/2006.py b/leetcode_py/2006.py
new file mode 100644
index 0000000..64957e7
--- /dev/null
+++ b/leetcode_py/2006.py
@@ -0,0 +1,11 @@
+from typing import List
+
+
+class Solution:
+    def countKDifference(self, nums: List[int], k: int) -> int:
+        count = 0  # number of pairs
+        for i in range(len(nums)):
+            for j in range(i + 1, len(nums)):
+                if abs(nums[i] - nums[j]) == k:
+                    count += 1
+        return count
diff --git a/luogu_py/p3717.py b/luogu_py/p3717.py
index ff2823d..fdd9710 100644
--- a/luogu_py/p3717.py
+++ b/luogu_py/p3717.py
@@ -1,27 +1,39 @@
-# Unfinish
 from typing import Tuple, List
 import math
 
-n, m, r = input().split(" ")
-locations: List[Tuple[str, str]] = []
-for i in range(int(m)):
-    location: Tuple[str, str] = tuple(input().split(" "))
-    locations.append(location)
+n, m, r = map(int, input().split())
+locations: List[Tuple[int, int]] = []
 
-map = [[0 for _ in range(int(n))] for _ in range(int(n))]
+for i in range(m):
+    x, y = map(int, input().split())
+    # 将输入的1-based坐标转换为0-based坐标
+    locations.append((x - 1, y - 1))
+
+grid = [[0 for _ in range(n)] for _ in range(n)]
 count = 0
 
-for i in range(int(n)):
-    for j in range(int(n)):
-        if map[i][j] == 0:
-            for k in range(int(m)):
-                distance = math.sqrt(
-                    (int(locations[k][0]) - i) ** 2 + (int(locations[k][1]) - j) ** 2
-                )
-                if distance <= float(r):
-                    map[i][j] = 1
-                    count = count + 1
-                    break
+for location in locations:
+    x, y = location
+    if grid[x][y] != 1:
+        grid[x][y] = 1
+        count += 1
+
+    # 检查半径r内的所有点
+    left = max(0, x - r)
+    right = min(n, x + r + 1)
+    top = max(0, y - r)
+    bottom = min(n, y + r + 1)
+
+    for i in range(left, right):
+        for j in range(top, bottom):
+            # 计算点(i,j)到探测器(x,y)的距离
+            distance = math.sqrt((i - x) ** 2 + (j - y) ** 2)
+            if distance <= r:  # 如果在探测范围内
+                if grid[i][j] != 1:
+                    grid[i][j] = 1
+                    count += 1
 
 print(count)
-print(map)
\ No newline at end of file
+for row in grid:
+    print(row)
+
diff --git a/luogu_py/p4530.py b/luogu_py/p4530.py
new file mode 100644
index 0000000..70af060
--- /dev/null
+++ b/luogu_py/p4530.py
@@ -0,0 +1,61 @@
+# TODO: 未完成
+def solve(n, m, balls):
+    # 将球按正负数和零分类并排序
+    pos = sorted([x for x in balls if x > 0], reverse=True)  # 正数降序
+    neg = sorted([x for x in balls if x < 0])  # 负数升序
+    zeros = [x for x in balls if x == 0]
+
+    # 如果正数不够分配给每个篮筐，需要特殊处理
+    if len(pos) < m:
+        # 需要用负数或零来确保每个篮筐都有球
+        return None  # 这里需要根据具体情况处理
+
+    # 初始化篮筐
+    baskets = [1] * m
+
+    # 优先处理负数对
+    neg_pairs = []
+    for i in range(0, len(neg) - 1, 2):
+        neg_pairs.append(neg[i] * neg[i + 1])
+
+    # 如果有单独的负数，与最小的正数配对或单独放在一个篮筐
+    if len(neg) % 2 == 1:
+        last_neg = neg[-1]
+        if pos and last_neg * pos[-1] > last_neg:
+            neg_pairs.append(last_neg * pos.pop())
+        else:
+            # 把单独的负数放在一个新的篮筐
+            smallest_basket_idx = 0
+            baskets[smallest_basket_idx] *= last_neg
+
+    # 将负数对的结果按从大到小排序
+    neg_pairs.sort(reverse=True)
+
+    # 分配负数对结果
+    for i, pair_product in enumerate(neg_pairs):
+        baskets[i % m] *= pair_product
+
+    # 分配零
+    zero_idx = 0
+    while zeros and zero_idx < m:
+        if baskets[zero_idx] == 1:  # 只在篮筐未使用时放零
+            baskets[zero_idx] *= zeros.pop()
+            zero_idx += 1
+
+    # 分配剩余的正数
+    pos_idx = 0
+    for num in pos:
+        baskets[pos_idx % m] *= num
+        pos_idx += 1
+
+    return sum(baskets)
+
+
+# 读取输入并处理
+while True:
+    n, m = map(int, input().split())
+    if n == 0 and m == 0:
+        break
+    balls = list(map(int, input().split()))
+    result = solve(n, m, balls)
+    print(result)