﻿ Python: Count number of substrings with same first and last characters of a given string - w3resource

# Python: Count number of substrings with same first and last characters of a given string

## Python String: Exercise-80 with Solution

Write a Python program to count number of substrings with same first and last characters of a given string.

Sample Solution:-

Python Code:

``````def no_of_substring_with_equalEnds(str1):
result = 0;
n = len(str1);
for i in range(n):
for j in range(i, n):
if (str1[i] == str1[j]):
result = result + 1
return result
str1 = input("Input a string: ")
print(no_of_substring_with_equalEnds(str1))
```
```

Sample Output:

```Input a string:  abc
3
```

Pictorial Presentation:

Flowchart:

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## Python: Tips of the Day

Check if a given key already exists in a dictionary:

In is the intended way to test for the existence of a key in a dict.

```d = {"key1": 10, "key2": 23}

if "key1" in d:
print("this will execute")

if "nonexistent key" in d:
print("this will not")
```

If you wanted a default, you can always use dict.get():

```d = dict()

for i in range(100):
key = i % 10
d[key] = d.get(key, 0) + 1
```

and if you wanted to always ensure a default value for any key you can either use dict.setdefault() repeatedly or defaultdict from the collections module, like so:

```from collections import defaultdict

d = defaultdict(int)

for i in range(100):
d[i % 10] += 1
```

but in general, the in keyword is the best way to do it.

Ref: https://bit.ly/2XPMRyz