This code implements a recursive algorithm to solve a problem involving sticks and a target length. The main idea is to check if it is possible to form the target length using the sticks provided as input.
Here is an analysis of the code:
1. The `solve` function is defined to recursively check if it's possible to form the target length with the sticks. It takes various parameters like the sticks list, number of sticks, total length, current length, visited array, number of used sticks, and current index.
2. The function uses backtracking to try out different combinations of sticks to form the target length. It checks certain conditions like if the current length equals the target length, the sum of sticks is divisible by the target, and if all sticks have been used correctly.
3. The function uses a nested loop to iterate over the sticks and apply certain rules to eliminate invalid combinations before proceeding with recursion.
4. The main while loop reads input, sorts the sticks list in descending order to optimize the search, and then iterates through the possible target lengths to find the minimum target length that can be formed.
5. The code uses backtracking to explore possible combinations and find the solution efficiently. If a valid combination is found, it prints the target length and breaks out of the loop.
Overall, the code efficiently solves the problem by exploring different combinations of sticks to form the target length using a recursive approach.
1 | |
2 | def solve(sticks, n, total_length, current_length, |
3 | visited, num_used_sticks, current_index): |
4 | |
5 | |
6 | if num_used_sticks == n and current_length == 0: |
7 | return True |
8 | |
9 | if total_length % target != 0: |
10 | return False |
11 | |
12 | |
13 | for i in range(current_index, n): |
14 | |
15 | if visited[i]: |
16 | continue |
17 | if current_length + sticks[i] > target: |
18 | continue |
19 | |
20 | if num_used_sticks == 0 and i != 0: |
21 | return False |
22 | if i > 0 and sticks[i] == sticks[i - 1] and not visited[i - 1]: |
23 | continue |
24 | |
25 | |
26 | visited[i] = True |
27 | num_used_sticks += 1 |
28 | current_length += sticks[i] |
29 | if current_length == target: |
30 | current_length = 0 |
31 | |
32 | |
33 | result = solve(sticks, n, total_length, current_length, |
34 | visited, num_used_sticks, |
35 | current_index = i + 1 if current_length != 0 else 0) |
36 | if result: |
37 | return True |
38 | |
39 | |
40 | if current_length == 0: |
41 | current_length = target - sticks[i] |
42 | else: |
43 | current_length -= sticks[i] |
44 | visited[i] = False |
45 | num_used_sticks -= 1 |
46 | |
47 | |
48 | return False |
49 | |
50 | while True: |
51 | n = int(input()) |
52 | if n == 0: |
53 | break |
54 | sticks = list(map(int, input().split())) |
55 | total_length = sum(sticks) |
56 | max_stick = max(sticks) |
57 | |
58 | visited = [False] * n |
59 | |
60 | sticks = sorted(sticks, reverse=True) |
61 | |
62 | for target in range(max_stick, total_length + 1): |
63 | if solve(sticks, n, total_length, 0, visited, 0, 0): |
64 | print(target) |
65 | break |