fix:下降路径最小和

05-动态规划/problem_solving_01.py

+"""
+下降路径最小和
+"""
+from linecache import cache
+from math import inf
+from typing import List
+
+
+class Solution:
+    def minFallingPathSum(self, matrix: List[List[int]]) -> int:
+        """
+        动态规划:
+        选或者不选?
+        枚举选哪个?
+        这道题使用枚举选哪个
+        :param matrix:
+        :return:
+        """
+        n = len(matrix)
+
+        @cache
+        def dfs(line: int, i: int) -> int:
+            """
+            每一个到顶层的路径和最小值
+            :param line: 行号
+            :param i: 列index
+            :return:
+            """
+            if i < 0 or i >= n:
+                return inf
+            if line == 0:
+                # 递归结束条件,到达顶层
+                return matrix[0][i]
+            return min(dfs(line - 1, i - 1), dfs(line - 1, i), dfs(line - 1, i + 1)) + matrix[line][i]
+
+        return min(dfs(n - 1, index) for index in range(n))
+
+
+if __name__ == '__main__':
+    result = Solution().minFallingPathSum([[2, 1, 3], [6, 5, 4], [7, 8, 9]])
+    print(result)