create dev channel

zeta/py/completed/7576.py

@@ -0,0 +1,53 @@
+import sys
+
+input = sys.stdin.readline
+
+
+def check(U):
+    for i in U:
+        for j in i:
+            if j == 0:
+                return False
+    return True
+
+
+def solve(M, N, U, ir):
+    step = 0
+    delta = (
+        (-1, 0),
+        (1, 0),
+        (0, -1),
+        (0, 1),
+    )
+    rotten = [ir]
+    while not check(U):
+        rotten.append([])
+        for r in rotten[step]:
+            for dm, dn in delta:
+                new = r[0] + dm, r[1] + dn
+                if 0 <= new[0] < M and 0 <= new[1] < N:
+                    if U[new[1]][new[0]] != 0:
+                        continue
+                    else:
+                        U[new[1]][new[0]] = 1
+                        rotten[step + 1].append(new)
+        if rotten[-1]:
+            step += 1
+        else:
+            return -1
+
+    return step
+
+
+if __name__ == "__main__":
+    M, N = map(int, input().split())
+    U = [[None for _ in range(M)] for _ in range(N)]  # U[h][n][m]
+    init_rottens = []
+
+    for n in range(N):
+        for m, v in enumerate(map(int, input().split())):
+            U[n][m] = v
+            if v == 1:
+                init_rottens.append((m, n))
+
+    print(solve(M, N, U, init_rottens))