day9: cpp changes, add part2 basic

day9/part1.cpp

@@ -1,6 +1,5 @@
 #include <algorithm>
 #include <iostream>
-#include <list>
 #include <string>
 #include <tuple>
 #include <vector>
@@ -8,6 +7,7 @@
 int main()
 {
     std::vector<std::pair<char, int>> steps;
+    std::vector<int> hashes (10000, 0);
 
     while (1) {
         std::string line;
@@ -19,13 +19,9 @@ int main()
     }
 
     int hx = 0, hy = 0, tx = 0, ty = 0;
-    std::list<std::pair<int, int>> locs;
-    locs.emplace_back(0, 0);
 
     for (const auto& [dir, count] : steps) {
         for (int i = 0; i < count; ++i) {
-            //std::cout << hx << ", " << hy << "    " << tx << ", " << ty << std::endl;
-
             if (dir == 'U')
                 ++hy;
             else if (dir == 'D')
@@ -41,14 +37,26 @@ int main()
                 if (hy != ty)
                     ty += hy > ty ? 1 : -1;
 
-                if (std::find(locs.cbegin(), locs.cend(), std::pair{tx, ty}) == locs.cend()) {
-                    locs.emplace_back(tx, ty);
+                int hash = tx * 1000 + ty;
+                for (int i = 0; i < hashes.size(); ++i) {
+                    if (hashes[i] == 0) {
+                        hashes[i] = hash;
+                        break;
+                    } else if (hashes[i] == hash) {
+                        break;
+                    }
                 }
             }
         }
     }
 
-    std::cout << locs.size() << std::endl;
+    int count = 0;
+    for (int i = 0; i < hashes.size(); ++i) {
+        ++count;
+        if (hashes[i] == 0)
+            break;
+    }
+    std::cout << count << std::endl;
 
     return 0;
 }

day9/part2.bas

@@ -0,0 +1,61 @@
+REM Advent of Code 2022: Day 9, part 1
+REM Written in Applesoft BASIC
+
+REM Same as part1, but track positions in SX and SY arrays.
+REM At 405, we reuse HX/HY/TX/TY to minimize changes from part1.
+
+ 10  DIM HS(7000)
+ 20  DIM SX(10)
+ 30  DIM SY(10)
+ 40  FOR I = 0 TO 9:SX(I) = 0: NEXT I
+ 50  FOR I = 0 TO 9:SY(I) = 0: NEXT I
+ 100 S$ = ""
+ 110  GET C$
+ 120  IF  ASC (C$) < 32 GOTO 200
+ 130 S$ = S$ + C$
+ 140  GOTO 110
+ 200  IF  LEN (S$) = 0 THEN  GOTO 1000
+ 210 D$ =  LEFT$ (S$,1)
+ 220 S =  VAL ( MID$ (S$,3, LEN (S$) - 2))
+ 230  PRINT ">>",D$;" ";S
+ 300  FOR I = 1 TO S
+ 310  IF D$ = "U" THEN SY(0) = SY(0) + 1: GOTO 400
+ 320  IF D$ = "D" THEN SY(0) = SY(0) - 1: GOTO 400
+ 330  IF D$ = "R" THEN SX(0) = SX(0) + 1: GOTO 400
+ 340  IF D$ = "L" THEN SX(0) = SX(0) - 1: GOTO 400
+ 350  PRINT "ERROR: ";D$
+ 360  END 
+ 400  FOR K = 1 TO 9
+ 405 HX = SX(K - 1):HY = SY(K - 1)
+ 410 TX = SX(K):TY = SY(K)
+ 415 DX = HX - TX:DY = HY - TY
+ 420  IF  ABS (DX) <  = 1 AND  ABS (DY) <  = 1 GOTO 460
+ 430  IF HX <  > TX THEN  GOSUB 500
+ 435  IF HY <  > TY THEN  GOSUB 550
+ 440 SX(K) = TX:SY(K) = TY
+ 445  NEXT K
+ 450 HH = TX * 1000 + TY
+ 455  GOSUB 600
+ 460  NEXT I
+ 470  GOTO 100
+ 500 Z =  - 1
+ 510  IF HX > TX THEN Z = 1
+ 520 TX = TX + Z
+ 530  RETURN 
+ 550 Z =  - 1
+ 560  IF HY > TY THEN Z = 1
+ 570 TY = TY + Z
+ 580  RETURN 
+ 600  FOR J = 0 TO 6999
+ 610  IF HS(J) = HH THEN J = 6999: GOTO 630
+ 620  IF HS(J) = 0 THEN HS(J) = HH:J = 9999
+ 630  NEXT J
+ 640  RETURN 
+ 1000 CO = 0
+ 1010  FOR I = 0 TO 9999
+ 1020 CO = CO + 1
+ 1030  IF HS(I) = 0 THEN I = 9999
+ 1040  NEXT I
+ 1050  PRINT "TOTAL: ";CO
+ 1060  END 
+

day9/part2.cpp

@@ -46,9 +46,10 @@ int main()
                         ty += hy > ty ? 1 : -1;
                 }
 
+            }
+
                 if (std::find(locs.cbegin(), locs.cend(), knots.back()) == locs.cend())
                     locs.emplace_back(knots.back());
-            }
         }
     }