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A - 温度管理と収穫判定 / Water Management and Harvest Value Aggregation Editorial by admin

DeepSeek V3

Overview

This problem involves processing queries that update the moisture levels of farm plots, perform closure operations, and compute the total harvest value of plots in a dry state within a specified range.

Analysis

Given the problem constraints (\(N, Q \leq 3000\)), a straightforward simulation of each operation is effective. Even if we process Operation 1 (range addition) and Operation 3 (range sum) with naive loops, the worst case results in \(3000 \times 3000 = 9 \times 10^6\) operations, which is well within the capability of modern computers. There is no need for sophisticated data structures — simple arrays and flag management are sufficient.

Algorithm

  1. Data Initialization: Store the harvest values \(S_i\) and moisture levels \(C_i\) in arrays, and prepare a boolean array closed to manage the closure state of each plot.
  2. Query Processing:
    • Operation 1 (1 l r v): For each plot from \(l\) to \(r\), if it is not closed, add \(v\) to its moisture level \(C_i\).
    • Operation 2 (2 x): Set plot \(x\) to the closed state.
    • Operation 3 (3 l r): For each plot from \(l\) to \(r\), if it is not closed and its moisture level is \(0\) or less, sum up the harvest values \(S_i\).

Complexity

  • Time complexity: \(O(N \cdot Q)\) (in the worst case, Operations 1 and 3 process the entire range every time)
  • Space complexity: \(O(N)\) (only arrays to store information for each plot are used)

Implementation Notes

  • Prepare a closed array to manage closure states, and set the flag in Operation 2.
  • In Operations 1 and 3, always check the closure state before processing.
  • Use sys.stdin.read() for input and process it efficiently with an iterator.
  • Accumulate output in a list and print it all at once at the end (for speed optimization).

This simple implementation runs efficiently enough within the given constraints. For larger constraints, advanced data structures such as lazy segment trees would be necessary, but they are not needed for this problem.

Source Code

import sys

def main():
    data = sys.stdin.read().split()
    if not data:
        return
    
    it = iter(data)
    N = int(next(it)); Q = int(next(it))
    S = [0] * (N+1)
    C = [0] * (N+1)
    closed = [False] * (N+1)
    
    for i in range(1, N+1):
        S[i] = int(next(it))
    for i in range(1, N+1):
        C[i] = int(next(it))
    
    output_lines = []
    
    for _ in range(Q):
        op = next(it)
        if op == '1':
            l = int(next(it)); r = int(next(it)); v = int(next(it))
            for i in range(l, r+1):
                if not closed[i]:
                    C[i] += v
        elif op == '2':
            x = int(next(it))
            closed[x] = True
        elif op == '3':
            l = int(next(it)); r = int(next(it))
            total = 0
            for i in range(l, r+1):
                if not closed[i] and C[i] <= 0:
                    total += S[i]
            output_lines.append(str(total))
    
    print("\n".join(output_lines))

if __name__ == "__main__":
    main()

This editorial was generated by deepseekv3.

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