题目：

解题过程：

模式A：

num = int(input("（模式A）输入数字："))               
for i in range(num):                         
    for j in range(num):                     
        if j < i + 1:                        
            print(j + 1, end=" ")            
        else:                                
            print("", end=" ")               
    print()                                  
                                             

模式B：

num = int(input("（模式B）输入数字："))              
for i in range(num):                        
    for j in range(num):                    
        if j < (num - i):                   
            if j != (num - i - 1):          
                print(j + 1, end=" ")       
            else:                           
                print(j + 1, end=" ")       
        else:                               
            print(" ", end=" ")             
    print()                                 

模式C：

num = int(input("（模式C）输入数字："))      
for i in range(1, num + 1):         
    for _ in range(num - i):        
        print(" ", end=" ")         
    for j in range(i, 0, -1):       
        print(j, end=" ")           
    print()                         
                                    

模式D：

num = int(input("（模式D）输入数字："))            
for i in range(num):                      
    for j in range(num):                  
        if j >= i:                        
            print(j - i + 1, end=" ")     
        else:                             
            print(" ", end=" ")           
    print()