update exercises

data/1.算法初阶/1.蓝桥杯/7段码/solution.md

@@ -21,30 +21,215 @@
 ## aop
 ### before
 ```cpp
-
+#include <iostream>
+using namespace std;
+int use[10];
+int ans, e[10][10], father[10];
+void init()
+{
+
+	e[1][2] = e[1][6] = 1;
+	e[2][1] = e[2][7] = e[2][3] = 1;
+	e[3][2] = e[3][4] = e[3][7] = 1;
+	e[4][3] = e[4][5] = 1;
+	e[5][4] = e[5][6] = e[5][7] = 1;
+	e[6][1] = e[6][5] = e[6][7] = 1;
+}
+
+int find(int a)
+{
+	if (father[a] == a)
+		return a;
+	father[a] = find(father[a]);
+	return father[a];
+}
 ```
 ### after
 ```cpp
+int main()
+{
+	init();
+	dfs(1);
+	cout << ans;
+	return 0;
+}
 
 ```
 
 ## 答案
 ```cpp
-
+void dfs(int d)
+{
+	if (d > 7)
+	{
+		for (int i = 1; i <= 7; i++)
+		{
+			father[i] = i;
+		}
+
+		for (int i = 1; i < 8; i++)
+		{
+			for (int j = 1; j < 8; j++)
+			{
+				if (e[i][j] == 1 && use[i] && use[j])
+				{
+					int fx = find(i);
+					int fy = find(j);
+					if (fx != fy)
+					{
+						father[fx] = fy;
+					}
+				}
+			}
+		}
+		int k = 0;
+		for (int i = 1; i < 8; i++)
+		{
+			if (use[i] && father[i] == i)
+			{
+				k++;
+			}
+		}
+		if (k == 1)
+		{
+			ans++;
+		}
+		return;
+	}
+
+	use[d] = 1;
+	dfs(d + 1);
+	use[d] = 0;
+	dfs(d + 1);
+}
 ```
 ## 选项
 
 ### A
 ```cpp
-
+void dfs(int d)
+{
+	if (d > 7)
+	{
+		for (int i = 1; i <= 7; i++)
+		{
+			father[i] = i;
+		}
+
+		for (int i = 1; i < 8; i++)
+		{
+			for (int j = 1; j < 8; j++)
+			{
+				if (e[i][j] == 1 && use[i] && use[j])
+				{
+					int fx = find(i);
+					int fy = find(j);
+					if (fx != fy)
+					{
+						father[fx] = fy;
+					}
+				}
+			}
+		}
+		int k = 0;
+		for (int i = 1; i < 8; i++)
+		{
+			if (father[i] == i)
+			{
+				k++;
+			}
+		}
+		if (k == 1)
+		{
+			ans++;
+		}
+		return;
+	}
+
+	use[d] = 1;
+	dfs(d + 1);
+	use[d] = 0;
+	dfs(d + 1);
+}
 ```
 
 ### B
 ```cpp
-
+void dfs(int d)
+{
+	if (d > 7)
+	{
+		for (int i = 1; i <= 7; i++)
+		{
+			father[i] = i;
+		}
+
+		for (int i = 1; i < 8; i++)
+		{
+			for (int j = 1; j < 8; j++)
+			{
+				if (e[i][j] == 1)
+				{
+					int fx = find(i);
+					int fy = find(j);
+					if (fx != fy)
+					{
+						father[fx] = fy;
+					}
+				}
+			}
+		}
+		int k = 0;
+		for (int i = 1; i < 8; i++)
+		{
+			if (use[i] && father[i] == i)
+			{
+				k++;
+			}
+		}
+		if (k == 1)
+		{
+			ans++;
+		}
+		return;
+	}
+
+	use[d] = 1;
+	dfs(d + 1);
+	use[d] = 0;
+	dfs(d + 1);
+}
 ```
 
 ### C
 ```cpp
-
+void dfs(int d)
+{
+	if (d > 7)
+	{
+		for (int i = 1; i <= 7; i++)
+		{
+			father[i] = i;
+		}
+
+		int k = 0;
+		for (int i = 1; i < 8; i++)
+		{
+			if (use[i] && father[i] == i)
+			{
+				k++;
+			}
+		}
+		if (k == 1)
+		{
+			ans++;
+		}
+		return;
+	}
+
+	use[d] = 1;
+	dfs(d + 1);
+	use[d] = 0;
+	dfs(d + 1);
+}
 ```