completed 2017.03.1

2017/02/2checksum.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+if __name__ == '__main__':
+    total = 0
+    with open("input", "r", encoding="utf-8") as sheet:
+        remainder = []
+        for line in sheet:
+            values = list(map(int, line.split()))
+            values.sort()
+            result = ""
+            i = 1
+            while i < len(values) and result == "":
+                j = 0
+                while j >= 0 and j < i and result == "":
+                    remainder = values[i] % values[j]
+                    if remainder == 0:
+                        result = int(values[i] / values[j])
+                    j += 1
+                i += 1
+            total += result
+    print(total)

2017/03/1spiral_memory.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+if __name__ == '__main__':
+    target = 277678
+    xstep = 1
+    ystep = 1
+    origin = [0, 0]
+    square = 1
+    pointer = origin
+
+    def inc_step(step):
+      if step >= 0:
+        return int(-1 * (step + 1))
+      else:
+        return int(-1 * (step - 1))
+
+    while square < target:
+      i = 1
+      while i <= abs(xstep) and square < target:
+        square += 1
+        if xstep >= 0:
+          pointer[0] += 1
+        else:
+          pointer[0] += -1
+        i += 1
+      xstep = inc_step(xstep)
+
+      i = 1
+      while i <= abs(ystep) and square < target:
+        square += 1
+        if ystep >= 0:
+          pointer[1] += 1
+        else:
+          pointer[1] += -1
+        i += 1
+      ystep = inc_step(ystep)
+
+    if square == target:
+      xloc = pointer[0]
+      yloc = pointer[1]
+      distance = abs(xloc) + abs(yloc)
+      print(f"dist to square {target} is {int(abs(xloc))}+{int(abs(yloc))}={distance}")

2017/03/notes

@@ -0,0 +1,62 @@
+spiral memory!
+
+i think i'll keep a live count of the current position relative to square 1,
+slowly stepping one by one through each square sequentially.
+my input is only 277678, so this should be fine!
+
+i notice that the pointer starts at square 1, at, say, (0,0),
+and then moves one square right, then one up,
+then two left, then two down,
+then three right, three up, etc
+
+seems like it follows the pattern:
+
+(x1 , y1 ) = (0      , 0     )
+(x2 , y2 ) = (x1 + 1 , y1    )
+(x3 , y3 ) = (x2     , y1 + 1)
+(x5 , y5 ) = (x3 - 2 , y3    )
+(x7 , y7 ) = (x5     , y3 - 2)
+(x10, y10) = (x5 + 3 , y7    )
+etc.
+
+i'll just for loop this shit
+something like: (copied to 1spiral_memory.py and worked further from there)
+(the following is my first rough sketch. see 1spiral_memory.py)
+
+target = 277678
+xstep = 1
+ystep = 1
+origin = (0, 0)
+square = 1
+pointer = origin
+
+def inc_step(step):
+  if step >= 0:
+    return int(-1 * (step + 1))
+  else:
+    return int(-1 * (step - 1))
+
+while square < target:
+  i = 1
+  while i <= abs(xstep) and square < target:
+    square += 1
+    if xstep >= 0:
+      pointer += (1, 0)
+    else:
+      pointer -= (1, 0)
+    i += 1
+  xstep = inc_step(xstep)
+
+  i = 1
+  while i <= abs(ystep) and square < target:
+    square += 1
+    if ystep >= 0:
+      pointer += (0, 1)
+    else:
+      pointer -= (0, 1)
+  ystep = inc_step(ystep)
+
+if square == target:
+  xloc = pointer[0]
+  yloc = pointer[1]
+  distance = abs(xloc) + abs(yloc)