結果

問題 No.2003 Frog on Grid
コンテスト
ユーザー gew1fw
提出日時 2025-06-12 20:01:31
言語 PyPy3
(7.3.15)
結果
TLE  
実行時間 -
コード長 2,866 bytes
コンパイル時間 187 ms
コンパイル使用メモリ 82,268 KB
実行使用メモリ 102,904 KB
最終ジャッジ日時 2025-06-12 20:05:09
合計ジャッジ時間 9,272 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 14 TLE * 1 -- * 11
権限があれば一括ダウンロードができます

ソースコード

diff # 

import sys
import bisect

MOD = 998244353

def main():
    H, W, K = map(int, sys.stdin.readline().split())
    grid = []
    for _ in range(H):
        line = sys.stdin.readline().strip()
        grid.append(line)
    
    # Precompute lines: for each s, list of (x, y) in order of increasing x
    max_s = H + W
    lines = [[] for _ in range(max_s + 1)]
    for x in range(1, H + 1):
        for y in range(1, W + 1):
            s = x + y
            if s >= 2 and s <= H + W:
                lines[s].append((x, y))
    
    # Sort each line by x
    for s in range(2, max_s + 1):
        lines[s].sort()
    
    # Initialize dp and prefix sums
    dp = [[0] * (W + 1) for _ in range(H + 1)]
    dp[1][1] = 1
    # For each line s, we'll maintain a list of x's and a prefix sum array
    line_prefix = {}  # s' : (list_x, prefix_sum)
    # Initialize line s=2
    s = 2
    list_x = []
    prefix_sum = []
    for (x, y) in lines[s]:
        if x == 1 and y == 1:
            list_x.append(x)
            prefix_sum.append(1)
        else:
            list_x.append(x)
            new_sum = (prefix_sum[-1] + dp[x][y]) if prefix_sum else dp[x][y]
            prefix_sum.append(new_sum)
    line_prefix[s] = (list_x, prefix_sum)
    
    for s in range(3, max_s + 1):
        if not lines[s]:
            continue
        list_x = []
        prefix_sum = []
        current_sum = 0
        for (x, y) in lines[s]:
            if grid[x-1][y-1] == '#':
                dp_val = 0
            else:
                total = 0
                for t in range(1, K + 1):
                    s_prime = s - t
                    if s_prime < 2:
                        break
                    if s_prime not in line_prefix:
                        continue
                    a = max(1, s_prime - y)
                    b = min(x, s_prime - 1)
                    if a > b:
                        continue
                    # Get the line's x list and prefix sum
                    x_list, pre_sum = line_prefix[s_prime]
                    # Find left and right indices
                    left = bisect.bisect_left(x_list, a)
                    right = bisect.bisect_right(x_list, b) - 1
                    if left > right:
                        continue
                    if left == 0:
                        sum_part = pre_sum[right]
                    else:
                        sum_part = pre_sum[right] - pre_sum[left - 1]
                    total += sum_part
                    if total >= MOD:
                        total -= MOD
                dp_val = total % MOD
            dp[x][y] = dp_val
            current_sum = (current_sum + dp_val) % MOD
            list_x.append(x)
            prefix_sum.append(current_sum)
        line_prefix[s] = (list_x, prefix_sum)
    
    print(dp[H][W] % MOD)

if __name__ == '__main__':
    main()
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