結果

問題 No.860 買い物
コンテスト
ユーザー lam6er
提出日時 2025-03-26 15:58:36
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 448 ms / 1,000 ms
コード長 2,691 bytes
コンパイル時間 300 ms
コンパイル使用メモリ 82,316 KB
実行使用メモリ 128,164 KB
最終ジャッジ日時 2025-03-26 15:59:36
合計ジャッジ時間 4,957 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge5
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 3
other AC * 15
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

class SegmentTree:
    def __init__(self, size):
        self.n = 1
        while self.n < size:
            self.n <<= 1
        self.size = size
        self.tree = [float('inf')] * (2 * self.n)
    
    def update(self, pos, value):
        pos += self.n
        self.tree[pos] = value
        while pos > 1:
            pos >>= 1
            left = self.tree[pos << 1]
            right = self.tree[(pos << 1) + 1]
            self.tree[pos] = min(left, right)
    
    def query_range(self, l, r):
        res = float('inf')
        l += self.n
        r += self.n
        while l <= r:
            if l % 2 == 1:
                res = min(res, self.tree[l])
                l += 1
            if r % 2 == 0:
                res = min(res, self.tree[r])
                r -= 1
            l >>= 1
            r >>= 1
        return res

def main():
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx])
    idx += 1
    C = []
    D = []
    for _ in range(N):
        c = int(input[idx])
        d = int(input[idx+1])
        C.append(c)
        D.append(d)
        idx += 2
    
    prefix_C = [0] * (N + 1)
    for i in range(N):
        prefix_C[i+1] = prefix_C[i] + C[i]
    
    prefix_D = [0] * (N + 1)
    for i in range(N):
        prefix_D[i+1] = prefix_D[i] + D[i]
    
    min_prefix = [0] * N
    min_prefix[0] = C[0]
    for i in range(1, N):
        min_prefix[i] = min(min_prefix[i-1], C[i])
    
    left = [-1] * N
    stack = []
    for i in range(N):
        while stack and C[stack[-1]] >= C[i]:
            stack.pop()
        if stack:
            left[i] = stack[-1]
        else:
            left[i] = -1
        stack.append(i)
    
    st = SegmentTree(N)
    dp = [0] * N
    val = [0] * N
    A_minus1 = -prefix_D[1]  # A[-1] = 0 - 0 - prefix_D[1] = -D[0]
    
    for i in range(N):
        l = left[i]
        q_l = max(l, 0)
        q_r = i - 1
        if q_l > q_r:
            group2_min = float('inf')
        else:
            group2 = st.query_range(q_l, q_r)
            group2_min = group2 + C[i] if group2 != float('inf') else float('inf')
        
        group1_min = val[l] if l >= 0 else float('inf')
        current_val = min(group2_min, group1_min)
        
        candidate_jm1 = A_minus1 + min_prefix[i]
        current_total = prefix_C[i+1] + prefix_D[i+1]
        dp_i = current_total + min(current_val, candidate_jm1)
        dp[i] = dp_i
        val[i] = current_val
        
        if i + 2 <= N:
            d_part = prefix_D[i+2]
        else:
            d_part = 0
        a_i = dp_i - prefix_C[i+1] - d_part
        st.update(i, a_i)
    
    print(dp[-1])

if __name__ == '__main__':
    main()
0