Add files for Feb ACSL

Author: sanjit-bhat

_posts/2018-12-05-code-style-guide.md

@@ -94,7 +94,7 @@ is `theorem_johnny_postulate.java`.
 Johnny Postulate
 ACSL theorem
 Contest #1 2018-19
-Acton Boxborough Regional High School
+Acton-Boxborough Regional High School
 Senior Division
 */
 

_posts/2019-02-24-feb-psets.md

@@ -0,0 +1,14 @@
+---
+layout:     post
+title:      PSETS for Feb ACSL
+date:       2019-02-24
+summary:    Topics include Boolean Algebra, Data Structures, and FSA/Regular Expressions.
+categories: comp3
+---
+
+Below are the self-contained guides to the February ACSL contest.
+They include topic explanations, useful resources, practice exercises, and answers.
+
+* [Boolean Algebra]({{ site.url }}/cpt-blog/tutorials/boolean-algebra.pdf)
+* [Data Structures]({{ site.url }}/cpt-blog/tutorials/data-structures.pdf)
+* [FSA/Regular Expressions]({{ site.url }}/cpt-blog/tutorials/fsa-regex.pdf)

_posts/2019-02-26-feb-contests.md

@@ -0,0 +1,28 @@
+---
+layout:     post
+title:      Practice Contests for Feb ACSL
+date:       2019-02-26
+author:     Sanjit Bhat
+summary:    Problems and solutions from 2016-17 and 2017-18 February ACSL
+categories: comp3
+---
+
+# 2016-17 Contest
+
+* [Short answers]({{ site.url }}/cpt-blog/contests/16-17/c3/c_3_sr.pdf)
+
+* [Short answer solutions]({{ site.url }}/cpt-blog/contests/16-17/c3/c_3_sr_sol.pdf)
+
+* [Coding problem]({{ site.url }}/cpt-blog/contests/16-17/c3/c_3_lights_out_sr.pdf) (including test data)
+
+* [Sanjit's solution]({{ site.url }}/cpt-blog/contests/16-17/c3/lights_sanjit_bhat.java) to coding problem
+
+# 2017-18 Contest
+
+* [Short answers]({{ site.url }}/cpt-blog/contests/17-18/c3/c_3_sr.pdf)
+
+* [Short answer solutions]({{ site.url }}/cpt-blog/contests/17-18/c3/c_3_sr_sol.pdf)
+
+* [Coding problem]({{ site.url }}/cpt-blog/contests/17-18/c3/c_3_walk_sr.pdf) (including test data)
+
+* [Sanjit's solution]({{ site.url }}/cpt-blog/contests/17-18/c3/walk_sanjit_bhat.java) to coding problem

contests/16-17/c3/c_3_lights_out_sr.pdf

@@ -0,0 +1,91 @@
+/*
+Sanjit Bhat
+ACSL Lights Out
+Contest #3 2016-17
+Acton-Boxborough Regional High School
+Senior Division
+*/
+
+import java.io.*;
+import java.math.BigInteger;
+import java.util.*;
+
+public class lights_sanjit_bhat {
+    static String your_name = "Sanjit Bhat";
+    static String prob_name = "lights";
+
+    public static void main(String[] args) throws IOException {
+        Scanner sc = new Scanner(new File(prob_name + ".in"));
+        PrintWriter out = new PrintWriter(new FileWriter(prob_name + ".out"), true);
+        out.println(your_name);
+
+        // read in all the boards, condense each into one string, and convert it to binary
+        String[] boards_bin = new String[6];
+        for (int i = 0; i < 6; i++) {
+            StringBuilder board_hex = new StringBuilder();
+            for (int j = 0; j < 4; j++) {
+                board_hex.append(sc.next());
+            }
+
+            // convert board to binary
+            String postfix = hexToBin(board_hex.toString());
+
+            // pad each binary string to make it fill entire board
+            StringBuilder zero_prefix = new StringBuilder();
+            for (int j = 0; j < 64 - postfix.length(); j++) {
+                zero_prefix.append("0");
+            }
+            boards_bin[i] = zero_prefix.toString() + postfix;
+        }
+
+        for (int test_case = 0; test_case < 5; test_case++) {
+            try {
+                String prev_board = boards_bin[test_case];
+                String future_board = boards_bin[test_case+1];
+
+                // calculate array of differences between strings
+                // this shows whether it was in change "radius"
+                boolean[] diffs = new boolean[64];
+                for (int char_pos = 0; char_pos < 64; char_pos++) {
+                    if (prev_board.charAt(char_pos) != future_board.charAt(char_pos)) {
+                        diffs[char_pos] = true;
+                    }
+                }
+
+                int press_loc = -1;
+                // find a diff that is the only one in its row - corresponds to top or bottom of star
+                // there might only be one (x in bottom-most or top-most part of screen) or two (change in middle of screen)
+                for (int i = 0; i < 8; i++) {
+                    int num_diffs = 0;
+                    int diff_loc = -1;
+                    for (int j = i*8; j < (i+1)*8; j++) {
+                        if (diffs[j]) {
+                            num_diffs++;
+                            diff_loc = j;
+                        }
+                    }
+
+                    // look at locations 2 rows above and 2 rows below for center of press
+                    if (num_diffs == 1) {
+                        if (diff_loc-16 >= 0 && diffs[diff_loc-16]) press_loc = diff_loc-16;
+                        if (diff_loc+16 < 64 && diffs[diff_loc+16]) press_loc = diff_loc+16;
+                    }
+                }
+
+                // convert from index notation to row, col notation
+                int row = (press_loc / 8) + 1;
+                int col = (press_loc % 8) + 1;
+                out.println(row + "" + col);
+            } catch (Exception e) {
+                out.println("Something's wrong with this test case");
+                e.printStackTrace();
+            }
+        }
+        sc.close();
+        out.close();
+    }
+
+    static String hexToBin(String s) {
+        return new BigInteger(s, 16).toString(2);
+    }
+}