# Python | Add list elements with a multi-list based on index

Given two lists, one is a simple list and second is a multi-list, the task is to add both lists based on index.

Example:

```Input:
List = [1, 2, 3, 4, 5, 6]
List of list = [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]

Output:
[[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]

Explanation:
[1] = [1+0]
[2, 3, 4] = [0+2, 1+2, 2+2]
[3, 4] = [3+0, 3+1]
[4, 5] = [4+0, 4+1]
[5, 6, 7] = [5+0, 5+1, 5+2]
[6] = [6+0]
```

Let’s discuss some methods to do this task.

Method #1: Using iteration

 `# Python code to add list elements  ` `# with a multi-list based on index  ` ` `  `# List initialization ` `List` `=` `[``1``, ``2``, ``3``, ``4``, ``5``, ``6``] ` `List_of_List ``=` `[[``0``], [``0``, ``1``, ``2``], [``0``, ``1``], ` `                ``[``0``, ``1``], [``0``, ``1``, ``2``], [``0``]] ` `Output ``=` `[] ` ` `  `# Iteration  ` `for` `x ``in` `range``(``len``(``List``)): ` `    ``temp ``=` `[] ` `    ``for` `y ``in` `List_of_List[x]: ` `        ``temp.append(y ``+` `List``[x]) ` `    ``Output.append(temp) ` ` `  `# Printing ` `print``(``"Initial list is:"``, ``List``) ` `print``(``"Initial list of list is :"``, List_of_List) ` `print``(``"Output is"``, Output) `

Output:

```Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]
```

Method #2: Using enumerate()

 `# Python code to add list elements  ` `# with a multi-list based on index ` ` `  `# List initialization ` `List` `=` `[``1``, ``2``, ``3``, ``4``, ``5``, ``6``] ` `List_of_List ``=` `[[``0``], [``0``, ``1``, ``2``], [``0``, ``1``], [``0``, ``1``], [``0``, ``1``, ``2``], [``0``]] ` `Output ``=` `[] ` ` `  `# using enumerate  ` `Output ``=` `[[elem ``+` `List``[x] ``for` `elem ``in` `y]  ` `          ``for` `x, y ``in` `enumerate``(List_of_List)] ` ` `  ` `  `# Printing ` `print``(``"Initial list is:"``, ``List``) ` `print``(``"Initial list of list is :"``, List_of_List) ` `print``(``"Output is"``, Output) `

Output:

```Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]
```

Method #3: Using `Zip()`

 `# Python code to add list elements  ` `# with a multi-list based on index ` ` `  `# List initialization ` `List` `=` `[``1``, ``2``, ``3``, ``4``, ``5``, ``6``] ` `List_of_List ``=` `[[``0``], [``0``, ``1``, ``2``], [``0``, ``1``], [``0``, ``1``], [``0``, ``1``, ``2``], [``0``]] ` `Output ``=` `[] ` ` `  `# using zip  ` `Output ``=` `[[z ``+` `x ``for` `z ``in` `y ]``for` `x, y ``in` `                 ``zip``(``List``, List_of_List)] ` ` `  `# Printing ` `print``(``"Initial list is:"``, ``List``) ` `print``(``"Initial list of list is :"``, List_of_List) ` `print``(``"Output is"``, Output) `

Output:

```Initial list is: [1, 2, 3, 4, 5, 6]
Initial list of list is : [[0], [0, 1, 2], [0, 1], [0, 1], [0, 1, 2], [0]]
Output is [[1], [2, 3, 4], [3, 4], [4, 5], [5, 6, 7], [6]]
```

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