832. Zuma Game (Recursive DP)

Given Zuma board string, return min balls to insert to clear all.

Input: Quoted string of R/G/B/Y/W.

Output: Integer.

Examples

Example 1

Input: "WRRBBW"
Output: 2
Explanation: 2 insertions.

Example 2

Input: "G"
Output: 2
Explanation: Need 2 more G.

Example 3

Input: ""
Output: 0
Explanation: Empty.