week 4 + 5

.envrc

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+# the shebang is ignored, but nice for editors
+
+if type -P lorri &>/dev/null; then
+  eval "$(lorri direnv)"
+else
+  echo 'while direnv evaluated .envrc, could not find the command "lorri" [https://github.com/nix-community/lorri]'
+  use nix
+fi

common/common.typ

@@ -6,8 +6,12 @@
   #doc
 ]
 
-#let embedClass(name: str) = {
+#let embedClass(name: str, label: none) = {
+  show figure: set block(width: 100%)
   show figure: set align(left)
   show figure.caption: set align(center)
-  figure(caption: name, raw(read("../" + name + ".java"), lang:"java", block: true))
+  [
+    #figure(caption: name, kind: "Class", supplement: [Class], raw(read("../" + name + ".java"), lang:"java", block: true))
+    #label
+  ]
 }

shell.nix

@@ -0,0 +1,11 @@
+{
+  pkgs ? import <nixpkgs> { },
+}:
+pkgs.mkShell rec {
+  buildInputs = with pkgs; [
+    jdk
+  ];
+  nativeBuildInputs = with pkgs; [
+    jre
+  ];
+}

week4/Card.java

@@ -67,6 +67,7 @@ public class Card {
     var top = "";
     top += value;
     if(this.value > 10) {
+      // face cards are empty
       top += "   ";
     } else {
       // and for numbered cards, show the suit characters
@@ -92,7 +93,7 @@ public class Card {
       // instead of using 3 rows we have a gap in the 3rd row
       output += " ";
       output += this.value >= 6 ? suit : " ";
-      // odd or 10
+      // odd or 10 have a symbol in the middle
       output += this.value % 2 == 1 || this.value == 10 ? suit : " ";
       output += this.value >= 6 ? suit : " ";
       output += " ";
@@ -113,7 +114,8 @@ public class Card {
   }
 
   // Shows cards next to each other (left to right)
-  // assumes that sprintCard returns the same width for each card (and each row of a card)
+  // for visuals, assumes that sprintCard returns the same width for each card (and each row of a card)
+  // for correctness, assumes that sprintCard always returns 4 rows (is asserted)
   public static String sprintCards(Card[] cards) {
     String[] output = { "", "", "", "" };
 
@@ -121,6 +123,7 @@ public class Card {
     // save the row into relevant output
     for(var i = 0; i < cards.length; i++) {
       var cardstr = cards[i].sprintCard().split("\n");
+      assert output.length == cardstr.length;
       for(var x = 0; x < cardstr.length; x++) {
         output[x] += cardstr[x] + " ";
       }

week4/Transpose.java

@@ -1,3 +1,24 @@
 public class Transpose {
+  public static void main(String[] args) {
+    int[][] input = {
+      {99, 85, 98},
+      {98, 57, 78},
+      {92, 77, 76},
+    };
 
+    for(var i = 0; i < input.length; i++) {
+      for(var j = i; j < input.length; j++) {
+        var og = input[i][j];
+        input[i][j] = input[j][i];
+        input[j][i] = og;
+      }
+    }
+
+    for(var i = 0; i < input.length; i++) {
+      for(var j = 0; j < input.length; j++) {
+        System.out.print(input[i][j] + " ");
+      }
+      System.out.println();
+    }
+  }
 }

week4/doc.typ

@@ -9,32 +9,50 @@
 Write a program `Deal` that takes an integer command-line argument `n` and
 prints `n` poker hands (five cards each) from a shuffled deck, separated by blank lines.
 
+A second class Card (@card) is used for visuals.
+
+Example run for 2 hands (`java Deal.java 2`):
+
+```
+J   J K   K ⒑♥ ♥⒑ 9♦ ♦9 7♠ ♠7 
+♥   ♥ ♠   ♠   ♥♥♥   ♦♦♦   ♠♠♠  
+♥   ♥ ♠   ♠   ♥♥♥   ♦ ♦        
+J   J K   K ⒑♥ ♥⒑ 9♦ ♦9 7♠ ♠7 
+
+3 ♥ 3 4♠ ♠4 4♦ ♦4 7♦ ♦7 6♦ ♦6 
+  ♥                ♦♦♦   ♦ ♦  
+                              
+3 ♥ 3 4♠ ♠4 4♦ ♦4 7♦ ♦7 6♦ ♦6 
+```
+
 #embedClass(name: "Deal")
 
-#embedClass(name: "Card")
+#embedClass(name: "Card", label: <card>)
 
 == Exercise 1.4.14
 
 Write a code fragment to print the transposition (rows and columns exchanged) of a square two-dimensional array.
-For the example spreadsheet array in the text, you code would print the following:
 
-```
-99 98 92 94 99 90 76 92 97 89
-85 57 77 32 34 46 59 66 71 29
-98 78 76 11 22 54 88 89 24 38
-```
+#place(
+  right,
+  figure(
+    table(
+      columns: 2,
+      [Example input],
+      [Output],
+      ```
+      99 85 98
+      98 57 78
+      92 77 76
+      ```,
+      ```
+      99 98 92
+      85 57 77
+      98 78 76
+      ```
+    ),
+    caption: [Example input and output matrix]
+  )
+)
 
-Input:
-
-```
-99 85 98
-98 57 78
-92 77 76
-94 32 11
-99 34 22
-90 46 54
-76 59 88
-92 66 89
-97 71 24
-89 29 38
-```
+#embedClass(name: "Transpose")

week4/tests/Transpose/input1.txt

@@ -1,10 +1,3 @@
 99 85 98
 98 57 78
 92 77 76
-94 32 11
-99 34 22
-90 46 54
-76 59 88
-92 66 89
-97 71 24
-89 29 38

week4/tests/Transpose/output1.txt

@@ -1,3 +1,3 @@
-99 98 92 94 99 90 76 92 97 89
-85 57 77 32 34 46 59 66 71 29
-98 78 76 11 22 54 88 89 24 38
+99 98 92
+85 57 77
+98 78 76

week5/CircleLines.java

@@ -0,0 +1,38 @@
+package week5;
+
+import common.StdDraw;
+
+public class CircleLines {
+  public static void main(String[] args) {
+    int n = Integer.parseInt(args[0]);
+    double p = Double.parseDouble(args[1]);
+    assert p >= 0. && p <= 1.;
+    StdDraw.setXscale(-1.1, 1.1);
+    StdDraw.setYscale(-1.1, 1.1);
+    StdDraw.clear();
+    double[][] points = new double[n][2];
+
+    for(var i = 0; i < n; i++) {
+      // explicitly convert to double
+      double fi = i;
+      // divide by total to get 0-1
+      fi /= n;
+      // and convert to radians
+      fi *= 2*Math.PI;
+      // save calculations
+      points[i][0] = Math.sin(fi);
+      points[i][1] = Math.cos(fi);
+      StdDraw.filledCircle(points[i][0], points[i][1], 0.01);
+    }
+
+    StdDraw.setPenColor(StdDraw.GRAY);
+    
+    for(var i = 0; i < n; i++) {
+      for(var x = i; x < n; x++) {
+        if(Math.random() > p) continue;
+
+        StdDraw.line(points[i][0], points[i][1], points[x][0], points[x][1]);
+      }
+    }
+  }
+}

week5/Circles.java

@@ -0,0 +1,27 @@
+package week5;
+
+import common.StdDraw;
+
+public class Circles {
+  public static void main(String[] args) {
+    var circleCount = Integer.parseInt(args[0]);
+    var pBlack = Double.parseDouble(args[1]);
+    var minRadius = Double.parseDouble(args[2]);
+    var maxRadius = Double.parseDouble(args[3]);
+
+    StdDraw.setScale();
+    StdDraw.clear();
+
+    for(var i = 0; i < circleCount; i++) {
+      if(Math.random() < pBlack) {
+        StdDraw.setPenColor(StdDraw.BLACK);
+      } else {
+        StdDraw.setPenColor(StdDraw.WHITE);
+      }
+      var radii = Math.random() * (maxRadius - minRadius) + minRadius;
+      var posX = Math.random();
+      var posY = Math.random();
+      StdDraw.filledCircle(posX, posY, radii);
+    }
+  }
+}

week5/MissingInt.java

@@ -0,0 +1,19 @@
+package week5;
+
+import common.StdIn;
+
+public class MissingInt {
+  public static void main(String[] args) {
+    int n = Integer.parseInt(args[0]);
+    boolean[] nums = new boolean[n];
+    for(var i = 0; i < n - 1; i++) {
+      int integer = StdIn.readInt() - 1;
+      nums[integer] = true;
+    }
+    for(var i = 0; i < nums.length; i++) {
+      if(!nums[i]) {
+        System.err.println(i + 1);
+      }
+    }
+  }
+}

week5/common

@@ -0,0 +1 @@
+../common

week5/doc.typ

@@ -0,0 +1,30 @@
+#import "./common/common.typ" : *
+
+#show: template
+
+= Week 5
+
+== Exercise 1.5.7
+
+Write a program that takes an integer command-line argument $n$, reads in
+$n-1$ distinct integers between 1 and $n$, and determines the missing value.
+
+#embedClass(name: "MissingInt")
+
+== Exercise 1.5.19
+
+Write a program that takes as command-line arguments an integer $n$ and
+a floating-point number $p$ (between $0$ and $1$), plots $n$ equally spaced points on the
+circumference of a circle, and then, with probability $p$ for each pair of points, draws
+a gray line connecting them.
+
+#embedClass(name: "CircleLines")
+
+== Exercise 1.5.26
+
+Write a program Circles that draws filled circles of random radii at random
+positions in the unit square, producing images like those below. Your program
+should take four command-line arguments: the number of circles, the probability
+that each circle is black, the minimum radius, and the maximum radius.
+
+#embedClass(name: "Circles")