5章の練習問題 (#9)

* add practices

* edit config.ts

* "+=" is difficulty to pronounce

* bits is not allowed

* add practice "exponentation"

* fix 日本語

* delete practice "Exponantation"

* add hint to divide-each-diff

* line-numbers

* deleted exponentation from index.md

docs/.vitepress/config.ts

@@ -128,6 +128,7 @@ export default withMermaid({
                     { text: '引数', link: '/text/chapter-5/argument' },
                     { text: '返り値', link: '/text/chapter-5/return-value' },
                     { text: '参照渡し', link: '/text/chapter-5/call-by-ref' },
+                    {text: '練習問題', link: '/text/chapter-5/practice/'}
                 ]
             },
             {

docs/text/chapter-5/practice/divide-each-difficulty.md

@@ -0,0 +1,83 @@
+# Divide each difficulty
+以下の$n \leq 7$を受け取って$n \times n$の行列$a_{i,j}=Fibonatti_{ij}$を出力するプログラムの、フィボナッチ数列の解を求める部分を別の関数`int fibonatti(int index);`に分離してみよう。
+```cpp:line-numbers
+#include <iostream>
+using namespace std;
+
+int main() {
+    int n;
+    cin >> n;
+    for (int i = 0; i < n; i++) {
+        for (int j = 0; j < n; j++) {
+            // ここから下を関数に切り分ける
+            // print (i*j)th of fibonatti sequence
+            int first = 1, second = 1;
+            for (int k = 0; k < i*j; k++) {
+                int next = first + second;
+                first = second;
+                second = next;
+            }
+            // ここから上を関数に切り分ける
+            cout << second << " ";
+        }
+        cout << endl;
+    }
+}
+```
+
+::: spoiler Hint
+下のコードの`// ここにフィボナッチ数列の計算を実装しよう`の部分を実装してみよう。
+```cpp:line-numbers
+#include <iostream>
+using namespace std;
+
+int fibonatti(int index) {
+    int first = 1, second = 1;
+    // ここにフィボナッチ数列の計算を実装しよう
+    return second;
+}
+
+int main() {
+    int n;
+    cin >> n;
+    for (i = 0; i < n; i++) {
+        for (j = 0; j < n; j++) {
+            int fib_ij = fibonatti(i*j);
+            cout << fib_ij << " ";
+        }
+        cout << endl;
+    }
+}
+```
+:::
+
+::: spoiler Answer
+
+```cpp:line-numbers
+#include <iostream>
+using namespace std;
+
+int fibonatti(int index) {
+    int first = 1, second = 1;
+    for (k = 0; k < index; k++) {
+        int next = first + second;
+        first = second;
+        second = next;
+    }
+    return second;
+}
+
+int main() {
+    int n;
+    cin >> n;
+    for (i = 0; i < n; i++) {
+        for (j = 0; j < n; j++) {
+            int fib_ij = fibonatti(i*j);
+            cout << fib_ij << " ";
+        }
+        cout << endl;
+    }
+}
+```
+
+:::

docs/text/chapter-5/practice/index.md

@@ -0,0 +1,4 @@
+# 練習問題 - Chapter 5
+
+- [Divide each difficulty](divide-each-difficulty)
+- [Operator+=](plus-equal)

docs/text/chapter-5/practice/plus-equal.md

@@ -0,0 +1,21 @@
+# Operator+=
+`int`型の`a`と`b`について`a`に`b`を足す操作である
+
+```cpp
+a += b;
+```
+
+で用いる`+=`演算子と同じ働きをする関数を書こう。
+
+::: spoiler Hint 1
+`a`を参照渡しで受け取ることで、`a`の値を書き換えることができる。
+:::
+
+::: spoiler Answer
+```cpp:line-numbers
+void compound_assigned_plus(int& lhs, int rhs) {
+    lhs = lhs + rhs;
+    return;
+}
+```
+:::