build

chapter_computational_complexity/iteration_and_recursion.md

@@ -102,7 +102,15 @@ status: new
 === "Dart"
 
     ```dart title="iteration.dart"
-    [class]{}-[func]{forLoop}
+    /* for 循环 */
+    int forLoop(int n) {
+      int res = 0;
+      // 循环求和 1, 2, ..., n-1, n
+      for (int i = 1; i <= n; i++) {
+        res += i;
+      }
+      return res;
+    }
     ```
 
 === "Rust"
@@ -216,7 +224,17 @@ status: new
 === "Dart"
 
     ```dart title="iteration.dart"
-    [class]{}-[func]{whileLoop}
+    /* while 循环 */
+    int whileLoop(int n) {
+      int res = 0;
+      int i = 1; // 初始化条件变量
+      // 循环求和 1, 2, ..., n-1, n
+      while (i <= n) {
+        res += i;
+        i++; // 更新条件变量
+      }
+      return res;
+    }
     ```
 
 === "Rust"
@@ -326,7 +344,19 @@ status: new
 === "Dart"
 
     ```dart title="iteration.dart"
-    [class]{}-[func]{whileLoopII}
+    /* while 循环（两次更新） */
+    int whileLoopII(int n) {
+      int res = 0;
+      int i = 1; // 初始化条件变量
+      // 循环求和 1, 4, ...
+      while (i <= n) {
+        res += i;
+        // 更新条件变量
+        i++;
+        i *= 2;
+      }
+      return res;
+    }
     ```
 
 === "Rust"
@@ -434,7 +464,18 @@ status: new
 === "Dart"
 
     ```dart title="iteration.dart"
-    [class]{}-[func]{nestedForLoop}
+    /* 双层 for 循环 */
+    String nestedForLoop(int n) {
+      String res = "";
+      // 循环 i = 1, 2, ..., n-1, n
+      for (int i = 1; i <= n; i++) {
+        // 循环 j = 1, 2, ..., n-1, n
+        for (int j = 1; j <= n; j++) {
+          res += "($i, $j), ";
+        }
+      }
+      return res;
+    }
     ```
 
 === "Rust"
@@ -557,7 +598,15 @@ status: new
 === "Dart"
 
     ```dart title="recursion.dart"
-    [class]{}-[func]{recur}
+    /* 递归 */
+    int recur(int n) {
+      // 终止条件
+      if (n == 1) return 1;
+      // 递：递归调用
+      int res = recur(n - 1);
+      // 归：返回结果
+      return n + res;
+    }
     ```
 
 === "Rust"
@@ -689,7 +738,13 @@ status: new
 === "Dart"
 
     ```dart title="recursion.dart"
-    [class]{}-[func]{tailRecur}
+    /* 尾递归 */
+    int tailRecur(int n, int res) {
+      // 终止条件
+      if (n == 0) return res;
+      // 尾递归调用
+      return tailRecur(n - 1, res + n);
+    }
     ```
 
 === "Rust"
@@ -813,7 +868,15 @@ status: new
 === "Dart"
 
     ```dart title="recursion.dart"
-    [class]{}-[func]{fib}
+    /* 斐波那契数列：递归 */
+    int fib(int n) {
+      // 终止条件 f(1) = 0, f(2) = 1
+      if (n == 1 || n == 2) return n - 1;
+      // 递归调用 f(n) = f(n-1) + f(n-2)
+      int res = fib(n - 1) + fib(n - 2);
+      // 返回结果 f(n)
+      return res;
+    }
     ```
 
 === "Rust"