# Problem 47473. Slitherlink IV: Recursive (medium size)

This challenge is to solve Slitherlink pencil puzzles. An essential starter guide is Slitherlink Techniques. An s matrix with values from 0:5 is provided. An s of 5 means this locations edges are not provided and may be from 0:3. The player will be given the s, c, and initial p matrices. The c matrix is clarified for the creation of the solution path of nodes as given in c. The p matrix is a [numel,numel] matrix of c indices where p(x,y)=1 is a possible node connection. p(1,2)=1 as well as example's p(1,5)=1. Additional details of p are provided in the function template. Function template also includes visualization code.
This Slitherlink IV: Recursive (medium size) is for the cases where s is not solved using only the Gimmes from Slitherlink Starting Techniques with a single Evolving but is solveable using Recursion with limited Guessing. Cases of Trivial, Gimmes, and single Evolve should be solved prior to invoking Recursion. When Evolve is used within a recursive routine that asserts incorrect content the Evolve may produce an invalid output for the invalid input. The two medium test cases are from Games World of Puzzles October 2020. I was unable to manually solve these puzzles on my first attempt prior to making an error thus I decided to program this simple pencil puzzle. This set of five Cody Challenges is the result of five days banging my keyboard to solve Slitherlink.
Input: s, matrix of edge counts of the unique solution path; (c,p,bsegs,emap,pmap) are provided but not required
Output: sv, a vector of path nodes where sv(1)=sv(end). These nodes correspond to values in the c matrix example.
Example:
%[1 5 9 13 17 % c matrix [3 1 1 2; % s matrix [1 2 6 7 8 12 16 20 19 18 17 13 9 5 1] % sv
% 2 6 10 14 18 %path nodes 2 1 0 1; %qty edges % sv matrix is vector of nodes generating the
% 3 7 11 15 19 % corners 1 2 1 2] %adjacent % Red Line path
% 4 8 12 16 20] %to path
Related Challenges:

### Solution Stats

100.0% Correct | 0.0% Incorrect
Last Solution submitted on Feb 23, 2023

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