Bitmask DP

dp[mask] — set mask பின் best; transition — bit சேர்.

Try this in Python

n = 3
INF = 10**9
dp = [INF] * (1 << n)
dp[0] = 0
for mask in range(1 << n):
    for j in range(n):
        if (mask >> j) & 1:
            continue
        nxt = mask | (1 << j)
        dp[nxt] = min(dp[nxt], dp[mask] + 1)
print(dp[(1 << n) - 1])

Key takeaways

• n ≤ ~20 — bitmask TSP.
• (pos, mask) graph.
• Rolling memory.