build

chapter_dynamic_programming/dp_problem_features.md

@@ -143,7 +143,23 @@ $$
 === "Swift"
 
     ```swift title="min_cost_climbing_stairs_dp.swift"
-    [class]{}-[func]{minCostClimbingStairsDP}
+    /* 爬楼梯最小代价：动态规划 */
+    func minCostClimbingStairsDP(cost: [Int]) -> Int {
+        let n = cost.count - 1
+        if n == 1 || n == 2 {
+            return cost[n]
+        }
+        // 初始化 dp 表，用于存储子问题的解
+        var dp = Array(repeating: 0, count: n + 1)
+        // 初始状态：预设最小子问题的解
+        dp[1] = 1
+        dp[2] = 2
+        // 状态转移：从较小子问题逐步求解较大子问题
+        for i in stride(from: 3, through: n, by: 1) {
+            dp[i] = min(dp[i - 1], dp[i - 2]) + cost[i]
+        }
+        return dp[n]
+    }
     ```
 
 === "Zig"
@@ -275,7 +291,18 @@ $$
 === "Swift"
 
     ```swift title="min_cost_climbing_stairs_dp.swift"
-    [class]{}-[func]{minCostClimbingStairsDPComp}
+    /* 爬楼梯最小代价：状态压缩后的动态规划 */
+    func minCostClimbingStairsDPComp(cost: [Int]) -> Int {
+        let n = cost.count - 1
+        if n == 1 || n == 2 {
+            return cost[n]
+        }
+        var (a, b) = (cost[1], cost[2])
+        for i in stride(from: 3, through: n, by: 1) {
+            (a, b) = (b, min(a, b) + cost[i])
+        }
+        return b
+    }
     ```
 
 === "Zig"
@@ -465,7 +492,25 @@ $$
 === "Swift"
 
     ```swift title="climbing_stairs_constraint_dp.swift"
-    [class]{}-[func]{climbingStairsConstraintDP}
+    /* 带约束爬楼梯：动态规划 */
+    func climbingStairsConstraintDP(n: Int) -> Int {
+        if n == 1 || n == 2 {
+            return n
+        }
+        // 初始化 dp 表，用于存储子问题的解
+        var dp = Array(repeating: Array(repeating: 0, count: 3), count: n + 1)
+        // 初始状态：预设最小子问题的解
+        dp[1][1] = 1
+        dp[1][2] = 0
+        dp[2][1] = 0
+        dp[2][2] = 1
+        // 状态转移：从较小子问题逐步求解较大子问题
+        for i in stride(from: 3, through: n, by: 1) {
+            dp[i][1] = dp[i - 1][2]
+            dp[i][2] = dp[i - 2][1] + dp[i - 2][2]
+        }
+        return dp[n][1] + dp[n][2]
+    }
     ```
 
 === "Zig"