Given a List, write a Python program to find the span of even elements in list, i.e distance between first and last occurrence of even element.

**Examples:**

Input: test_list = [1, 3, 7, 4, 7, 2, 9, 1, 10, 11]Output: 5Explanation: Even elements begin at 4 and end at 10, spanning 5 indices.

Input: test_list = [1, 3, 7, 4, 7, 2, 9, 1, 1, 11]Output: 2Explanation: Even elements begin at 4 and end at 2, spanning 2 indices.

**Method #1: Using ****list comprehension**

In this we get all the indices of all even elements using list comprehension and then perform difference of first and last index of matched elements in list.

## Python3

`# Python3 code to demonstrate working of` `# Even elements span in list` `# Using list comprehension` ` ` `# initializing Matrix` `test_list ` `=` `[` `1` `, ` `3` `, ` `7` `, ` `4` `, ` `7` `, ` `2` `, ` `9` `, ` `1` `, ` `10` `, ` `11` `]` ` ` `# printing original list` `print` `(` `"The original list is : "` `+` `str` `(test_list))` ` ` `# getting even indices` `indices_list ` `=` `[idx ` `for` `idx ` `in` `range` `(` ` ` `len` `(test_list)) ` `if` `test_list[idx] ` `%` `2` `=` `=` `0` `]` ` ` `# getting difference of first and last occurrence` `res ` `=` `indices_list[` `-` `1` `] ` `-` `indices_list[` `0` `]` ` ` `# printing result` `print` `(` `"Even elements span : "` `+` `str` `(res))` |

**Output**

The original list is : [1, 3, 7, 4, 7, 2, 9, 1, 10, 11] Even elements span : 5

**Method #2 : Using ****filter()**** + ****lambda**

In this, we perform task of getting indices of elements using filter() and lambda.

## Python3

`# Python3 code to demonstrate working of` `# Even elements span in list` `# Using filter() + lambda` ` ` `# initializing Matrix` `test_list ` `=` `[` `1` `, ` `3` `, ` `7` `, ` `4` `, ` `7` `, ` `2` `, ` `9` `, ` `1` `, ` `10` `, ` `11` `]` ` ` `# printing original list` `print` `(` `"The original list is : "` `+` `str` `(test_list))` ` ` `# getting even indices` `indices_list ` `=` `list` `(` ` ` `filter` `(` `lambda` `x: test_list[x] ` `%` `2` `=` `=` `0` `, ` `range` `(` `len` `(test_list))))` ` ` `# getting difference of first and last occurrence` `res ` `=` `indices_list[` `-` `1` `] ` `-` `indices_list[` `0` `]` ` ` `# printing result` `print` `(` `"Even elements span : "` `+` `str` `(res))` |

**Output**

The original list is : [1, 3, 7, 4, 7, 2, 9, 1, 10, 11] Even elements span : 5

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