Submission #626060

#	Time	Username	Problem	Language	Result	Execution time	Memory
626060		54skyxenon	Mecho (IOI09_mecho)	Cpython 3	0 / 100	1099 ms	17120 KiB

mecho

# https://oj.uz/problem/view/IOI09_mecho

from collections import deque
from math import ceil

n, s = map(int, input().split())

forest = []
for _ in range(n):
    forest.append(input())

start = None
end = None
hives = []

for i in range(n):
    for j in range(n):
        if forest[i][j] == 'M':
            start = (i, j)
        if forest[i][j] == 'D':
            end = (i, j)
        if forest[i][j] == 'H':
            hives.append((i, j))

dist_hive = [[float('inf')] * n for _ in range(n)]

hives_Q = deque()
for i, j in hives:
    dist_hive[i][j] = 0
    hives_Q.append((i, j, 0))

while hives_Q:
    r, c, depth = hives_Q.popleft()
    for nr, nc in [(r + 1, c), (r - 1, c), (r, c + 1), (r, c - 1)]:
        if 0 <= nr < n and 0 <= nc < n and forest[nr][nc] == 'G' and dist_hive[nr][nc] == float('inf'):
            hives_Q.append((nr, nc, depth + 1))
            dist_hive[nr][nc] = depth + 1

def bs(lo, hi):
    if not ok(lo):
        return -1
    
    global dist_hive

    def ok(midd):
        seen = [[False] * n for _ in range(n)]
        seen[start[0]][start[1]] = True

        mecho_Q = deque([(start[0], start[1], 0)])
        while mecho_Q:
            r, c, depth = mecho_Q.popleft()
            if (r, c) == end:
                return True

            for nr, nc in [(r + 1, c), (r - 1, c), (r, c + 1), (r, c - 1)]:
                if 0 <= nr < n and 0 <= nc < n and forest[nr][nc] in {'G', 'D'} and (midd + ((depth + 1) // s)) < dist_hive[nr][nc] and not seen[nr][nc]:
                    seen[nr][nc] = True
                    mecho_Q.append((nr, nc, depth + 1))

        return False

    while lo < hi:
        mid = lo + (hi - lo + 1) // 2

        if ok(mid):
            lo = mid
        else:
            hi = mid - 1

    return lo

print(bs(0, n ** 2))

• Subtask 1: 0 / 100