day 10

day10/input

@@ -0,0 +1,58 @@
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day10/sample1.in

@@ -0,0 +1,4 @@
+0123
+1234
+8765
+9876

day10/sample2.in

@@ -0,0 +1,7 @@
+...0...
+...1...
+...2...
+6543456
+7.....7
+8.....8
+9.....9

day10/sample3.in

@@ -0,0 +1,7 @@
+..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....

day10/sample4.in

@@ -0,0 +1,7 @@
+10..9..
+2...8..
+3...7..
+4567654
+...8..3
+...9..2
+.....01

day10/sample5.in

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

day10/sol.py

@@ -0,0 +1,56 @@
+import itertools 
+from collections import Counter
+def read(file):
+    return [line.strip() for line in file]
+
+def solve(file):
+    grid = read(file)
+    ny = len(grid)
+    nx = len(grid[0])
+    points = lambda: itertools.product(range(nx), range(ny))
+
+    def get(x,y):
+        if 0 <= x < nx and 0 <= y < ny:
+            return grid[y][x]
+        return '.'
+
+    def visit(x,y,h,n):
+        c = get(x,y)
+        if c == h:
+            assert (x,y) not in done
+            queue.append((x,y))
+            count[x,y] += n
+
+    trailheads = [(x,y) for x,y in points() if get(x,y) == '0']
+
+    t1 = 0
+    t2 = 0
+    for p in trailheads:
+        queue = [p]
+        done = set()
+        count = Counter()
+        count[p] = 1
+        while queue:
+            x,y = queue.pop(0)
+            #print(x,y,queue)
+            if (x,y) in done:
+                continue
+            done.add((x,y))
+            n = count[x,y]
+            c = get(x,y)
+            if c != '.' and c != '9':
+                h = str(int(c)+1)
+                visit(x+1,y,h,n)
+                visit(x-1,y,h,n)
+                visit(x,y+1,h,n)
+                visit(x,y-1,h,n)
+        for x,y in points():
+            if get(x,y) == '9' and (x,y) in done:
+                t1 += 1
+                t2 += count[x,y]
+                
+    print(t1)
+    print(t2)
+
+solve(open("sample5.in"))
+solve(open("input"))