决策树ID3（C++实现）

14 5 Outlook 3 Sunny Overcast Rain Temperature 3 Hot Mild Cool Humidity 2 High Normal Wind 2 Weak Strong PlayTennis 2 Yes No Sunny Hot High Weak No Sunny Hot High Strong No Overcast Hot High Weak Yes Rain Mild High Weak Yes Rain Cool Normal Weak Yes Rain Cool Normal Strong No Overcast Cool Normal Strong Yes Sunny Mild High Weak No Sunny Cool Normal Weak Yes Rain Mild Normal Weak Yes Sunny Mild Normal Strong Yes Overcast Mild High Strong Yes Overcast Hot Normal Weak Yes Rain Mild High Strong No 5 Sunny Hot High Weak Sunny Hot High Strong Sunny Mild High Weak Sunny Cool Normal Weak Sunny Mild Normal Strong