Beginner0-1 BFS practice · C++17Best score: not submitted
Client-side educational grading. Submit runs your C++17 program against ten predefined tests in your browser. Tests are intentionally visible through See Hidden Tests. Scores are local practice records, not secure competition results.
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C++ Suggestion Library
main.cpp · C++17
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Ten tests, ten points each. Output is checked against the expected answer. Custom runs never change your score.
Test
Result
Points
Execution time
Each test has a 5-second execution limit, 256 MiB linked program WASM memory maximum, and 1 MiB combined output limit. Allocated WASM memory is not peak browser memory. Deep recursion can overflow the WASM stack; an iterative traversal is safer for long paths.
Problem statement
You are given a directed graph with N vertices and M edges. Each edge has a weight of either 0 or 1. Find the minimum total cost of traveling from S to T. If T is unreachable, output -1. Self-loops and repeated edges are allowed.
Input format
First line: N M. Next M lines: U V W. Last line: S T.
Output format
Print one integer: the minimum total cost or -1.
Constraints
1 ≤ N ≤ 100000
0 ≤ M ≤ 200000
1 ≤ U, V, S, T ≤ N
W is either 0 or 1.
Sample input
5 6
1 2 1
1 3 0
3 2 0
2 4 1
3 5 1
5 4 0
1 4
Sample output
1
Sample explanation
Take 1 → 3 → 2 → 4: the costs are 0 + 0 + 1 = 1. No zero-cost route reaches 4.
Need a hint?
0-1 BFS using a deque. Expected complexity: O(N + M).