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# C++ - `For Loop` Exercises

> There are 9 problems, from easy to hard. Good luck and have fun Coding!

## Question 1 (Easy)
#### 輸入一個正整數n，輸出n個 `*`

- Example 1
    - Input: `2`
    - Output: `**`
- Example 2 
    - Input: `10`
    - Output: `**********`

## Question 2 (Easy)
#### 輸入兩個整數$a$, $b\ (a<b)$，輸出$[a, b]$之間(包含$a$跟$b$)的所有**整數**

- Example 1
    - Input: `3 10`
    - Output: `3 4 5 6 7 8 9 10`
- Example 2 
    - Input: `-3 2`
    - Output: `-3 -2 -1 0 1 2`

## Question 3 (Easy)
#### 輸入兩個整數$a$, $b\ (a<b)$，將$[a, b]$之間(包含$a$跟$b$)的所有數字反過來輸出

- Example 1
    - Input: `3 10`
    - Output: `10 9 8 7 6 5 4 3`
- Example 2 
    - Input: `-5 5`
    - Output: `5 4 3 2 1 0 -1 -2 -3 -4 -5`

## Question 4 (Easy)
#### 輸入兩個整數$a$, $b\ (a<b)$，輸出$[a, b]$之間(包含$a$跟$b$)的所有**偶數**

- Example 1 (Easy)
    - Input: `3 10`
    - Output: `4 6 8 10`
- Example 2 
    - Input: `-3 2`
    - Output: `-2 0 2`

## Question 5 (Medium)
#### 輸入兩個正整數$a$, $b\ (a<b)$，輸出$[a, b]$之間(包含$a$跟$b$)的所有**3的倍數**

- Example 1
    - Input: `3 10`
    - Output: `3 6 9`
- Example 2 
    - Input: `15 26`
    - Output: `15 18 21 24`



## Question 6 (Medium)
#### 輸入一個整數$a$，輸出$a$的九九乘法表的值(ax1, ax2, ax3, ..., ax9)

- Example 1
    - Input: `3`
    - Output: 
        ```
        3 x 1 = 3
        3 x 2 = 6
        3 x 3 = 9
        3 x 4 = 12
        3 x 5 = 15
        3 x 6 = 18
        3 x 7 = 21
        3 x 8 = 24
        3 x 9 = 27
        ```
- Example 2
    - Input: `7`
    - Output: 
        ```
        7 x 1 = 7
        7 x 2 = 14
        7 x 3 = 21
        7 x 4 = 28
        7 x 5 = 35
        7 x 6 = 42
        7 x 7 = 49
        7 x 8 = 56
        7 x 9 = 63
        ```
        
        
---

##### For the following problem, try to use nested for loops (for loop in a for loop)        
        
## Question 7 (Medium)
#### 輸入一個整數$a$，輸出一座高度為$a$的三角形

- Example 1
    - Input: `3`
    - Output: 
        ```
        *
        **
        ***
        ```
- Example 2
    - Input: `7`
    - Output: 
        ```
        *
        **
        ***
        ****
        *****
        ******
        *******
        ```
        
        
## Question 7-2 (Medium)
#### 輸入一個整數$a$，輸出一座高度為$a$的三角形

- Example 1
    - Input: `3`
    - Output: 
        ```
        *
        ***
        *****
        ```
- Example 2
    - Input: `7`
    - Output: 
        ```
        *
        ***
        *****
        *******
        *********
        ***********
        *************
        ```
        

## Question 8 (Hard)
#### 輸入一個整數$a$，輸出一座高度為$a$的金字塔

- Example 1
    - Input: `3`
    - Output: 
        ```
          *
         ***
        *****
        ```
- Example 2
    - Input: `7`
    - Output: 
        ```
              *
             ***
            *****
           *******
          *********
         ***********
        *************
        ```
        
## Question 9 (Hard)
#### 印出九九乘法表

- Example 1
    - Output: 
        ```
        2*1= 2 3*1= 3 4*1= 4 5*1= 5 6*1= 6 7*1= 7 8*1= 8 9*1= 9 
        2*2= 4 3*2= 6 4*2= 8 5*2=10 6*2=12 7*2=14 8*2=16 9*2=18
        2*3= 6 3*3= 9 4*3=12 5*3=15 6*3=18 7*3=21 8*3=24 9*3=27
        2*4= 8 3*4=12 4*4=16 5*4=20 6*4=24 7*4=28 8*4=32 9*4=36
        2*5=10 3*5=15 4*5=20 5*5=25 6*5=30 7*5=35 8*5=40 9*5=45
        2*6=12 3*6=18 4*6=24 5*6=30 6*6=36 7*6=42 8*6=48 9*6=54
        2*7=14 3*7=21 4*7=28 5*7=35 6*7=42 7*7=49 8*7=56 9*7=63
        2*8=16 3*8=24 4*8=32 5*8=40 6*8=48 7*8=56 8*8=64 9*8=72
        2*9=18 3*9=27 4*9=36 5*9=45 6*9=54 7*9=63 8*9=72 9*9=81
        ```