feat: Add solution for LeetCode #799

Author: 0xMashiro

SOLVED.md

@@ -88,6 +88,7 @@
 | 740 | [Delete and Earn](https://leetcode.com/problems/delete-and-earn/) | [Code](src/leetcode/problems/delete-and-earn.cpp) / [Test](test/leetcode/problems/delete-and-earn.cpp) |
 | 744 | [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/) | [Code](src/leetcode/problems/find-smallest-letter-greater-than-target.cpp) / [Test](test/leetcode/problems/find-smallest-letter-greater-than-target.cpp) |
 | 756 | [Pyramid Transition Matrix](https://leetcode.com/problems/pyramid-transition-matrix/) | [Code](src/leetcode/problems/pyramid-transition-matrix.cpp) / [Test](test/leetcode/problems/pyramid-transition-matrix.cpp) |
+| 799 | [Champagne Tower](https://leetcode.com/problems/champagne-tower/) | [Code](src/leetcode/problems/champagne-tower.cpp) / [Test](test/leetcode/problems/champagne-tower.cpp) |
 | 816 | [Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates/) | [Code](src/leetcode/problems/ambiguous-coordinates.cpp) / [Test](test/leetcode/problems/ambiguous-coordinates.cpp) |
 | 829 | [Consecutive Numbers Sum](https://leetcode.com/problems/consecutive-numbers-sum/) | [Code](src/leetcode/problems/consecutive-numbers-sum.cpp) / [Test](test/leetcode/problems/consecutive-numbers-sum.cpp) |
 | 837 | [New 21 Game](https://leetcode.com/problems/new-21-game/) | [Code](src/leetcode/problems/new-21-game.cpp) / [Test](test/leetcode/problems/new-21-game.cpp) |

include/leetcode/problems/champagne-tower.h

@@ -0,0 +1,18 @@
+#include "leetcode/core.h"
+
+namespace leetcode {
+namespace problem_799 {
+
+using Func = std::function<double(int, int, int)>;
+
+class ChampagneTowerSolution : public SolutionBase<Func> {
+ public:
+  //! 799. Champagne Tower
+  //! https://leetcode.com/problems/champagne-tower/
+  double champagneTower(int poured, int query_row, int query_glass);
+
+  ChampagneTowerSolution();
+};
+
+}  // namespace problem_799
+}  // namespace leetcode

src/leetcode/problems/champagne-tower.cpp

@@ -0,0 +1,44 @@
+#include "leetcode/problems/champagne-tower.h"
+
+namespace leetcode {
+namespace problem_799 {
+
+// 模拟法：逐层计算每个杯子的香槟量
+// 用dp[i][j]表示第i行第j个杯子收到的总香槟量（可能超过1）
+// 如果dp[i][j] > 1，则溢出部分(dp[i][j] - 1) / 2分别流入下一行的两个杯子
+// 时间复杂度: O(query_row^2)，空间复杂度: O(query_row)
+static double solution1(int poured, int query_row, int query_glass) {
+  // 由于只需要前一行的数据，可以用一维数组优化空间
+  // 但为了清晰，先用二维思路，用vector存储当前行
+  vector<double> current_row(1, poured);  // 第0行只有1个杯子，初始倒入poured
+  
+  for (int row = 0; row < query_row; ++row) {
+    vector<double> next_row(row + 2, 0.0);  // 下一行有row+2个杯子
+    for (int glass = 0; glass <= row; ++glass) {
+      if (current_row[glass] > 1.0) {
+        // 溢出部分平均分给下一行的左右两个杯子
+        double overflow = (current_row[glass] - 1.0) / 2.0;
+        next_row[glass] += overflow;      // 左下方的杯子
+        next_row[glass + 1] += overflow;  // 右下方的杯子
+      }
+    }
+    current_row = std::move(next_row);
+  }
+  
+  // 返回结果，但最多为1（杯子满了）
+  return min(1.0, current_row[query_glass]);
+}
+
+ChampagneTowerSolution::ChampagneTowerSolution() {
+  setMetaInfo({.id = 799,
+               .title = "Champagne Tower",
+               .url = "https://leetcode.com/problems/champagne-tower/"});
+  registerStrategy("Simulation", solution1);
+}
+
+double ChampagneTowerSolution::champagneTower(int poured, int query_row, int query_glass) {
+  return getSolution()(poured, query_row, query_glass);
+}
+
+}  // namespace problem_799
+}  // namespace leetcode

test/leetcode/problems/champagne-tower.cpp

@@ -0,0 +1,77 @@
+#include "leetcode/problems/champagne-tower.h"
+
+#include "gtest/gtest.h"
+
+namespace leetcode {
+namespace problem_799 {
+
+class ChampagneTowerTest : public ::testing::TestWithParam<std::string> {
+ protected:
+  void SetUp() override { solution.setStrategy(GetParam()); }
+
+  ChampagneTowerSolution solution;
+};
+
+TEST_P(ChampagneTowerTest, Example1) {
+  // poured = 1, query_row = 1, query_glass = 1
+  // 倒1杯到顶层，顶层满了，没有溢出，所以第1行第1个杯子是空的
+  int poured = 1;
+  int query_row = 1;
+  int query_glass = 1;
+  double expected = 0.0;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+TEST_P(ChampagneTowerTest, Example2) {
+  // poured = 2, query_row = 1, query_glass = 1
+  // 倒2杯到顶层，顶层满1杯，溢出1杯，平均分给下一行两个杯子，各0.5杯
+  int poured = 2;
+  int query_row = 1;
+  int query_glass = 1;
+  double expected = 0.5;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+TEST_P(ChampagneTowerTest, Example3) {
+  // poured = 100000009, query_row = 33, query_glass = 17
+  // 大量香槟，中间位置会满
+  int poured = 100000009;
+  int query_row = 33;
+  int query_glass = 17;
+  double expected = 1.0;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+TEST_P(ChampagneTowerTest, ZeroPoured) {
+  // 没有倒香槟，所有杯子都是空的
+  int poured = 0;
+  int query_row = 0;
+  int query_glass = 0;
+  double expected = 0.0;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+TEST_P(ChampagneTowerTest, TopGlassFull) {
+  // 倒1杯，顶层满了
+  int poured = 1;
+  int query_row = 0;
+  int query_glass = 0;
+  double expected = 1.0;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+TEST_P(ChampagneTowerTest, SecondRowBothHalf) {
+  // 倒2杯，第1行两个杯子各0.5
+  int poured = 2;
+  int query_row = 1;
+  int query_glass = 0;
+  double expected = 0.5;
+  EXPECT_DOUBLE_EQ(expected, solution.champagneTower(poured, query_row, query_glass));
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    LeetCode, ChampagneTowerTest,
+    ::testing::ValuesIn(ChampagneTowerSolution().getStrategyNames()));
+
+}  // namespace problem_799
+}  // namespace leetcode