FastPrep

Description

Solutions

Count Substrings

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Count substrings that satisfy the following two conditions:

Count of 1s and count of 0s is equal.
Should be a block of 0s followed by a block of 1s or vice versa.

Examples of such substrings are "0011", "01", "10", "1100".

You can count repetitions, for example, "10101" has 4 such substrings: "10", "01", "10", "01".

Function Description

Complete the function countSubstrings in the editor.

countSubstrings has the following parameter:

String s: the binary string to be checked

Returns

int: the number of substrings that satisfy the conditions

Example 1:

Input:  s = "10101"
Output: 4 
Explanation:
      The string "10101" contains the following substrings that satisfy the conditions:
      
        "10": A block of 1 followed by a block of 0.
        "01": A block of 0 followed by a block of 1.
        "10": Another block of 1 followed by a block of 0.
        "01": Another block of 0 followed by a block of 1.
      
      There are a total of 4 such substrings, so the answer is 4.

Constraints:

N/A