LeetCode 1434.
Решал контест на LeetCode и встретил интересную задачку.
Моё решение:
Моё решение:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | class Solution { private static final int MODULO = (int) 1e9 + 7; public int numberWays(List<List<Integer>> hats) { int nPeople = hats.size(); boolean[][] preferred = new boolean[nPeople][41]; for (int i = 0; i < nPeople; i++) { for (int hat : hats.get(i)) { preferred[i][hat] = true; } } return numberWays(40, preferred); } private int numberWays(int nHats, boolean[][] preferred) { int[][] dp = new int[nHats + 1][1 << preferred.length]; for (int[] hatDp : dp) { Arrays.fill(hatDp, -1); } return numberWays(nHats, (1 << preferred.length) - 1, preferred, dp); } private int numberWays(int nHats, int gotHatMask, boolean[][] preferred, int[][] dp) { if (nHats == 0) { return gotHatMask == 0 ? 1 : 0; } if (dp[nHats][gotHatMask] == -1) { int sum = numberWays(nHats - 1, gotHatMask, preferred, dp); for (int i = 0; i < preferred.length; i++) { if (preferred[i][nHats] && getBit(gotHatMask, i) == 1) { sum += numberWays(nHats - 1, clearBit(gotHatMask, i), preferred, dp); sum %= MODULO; } } dp[nHats][gotHatMask] = sum; } return dp[nHats][gotHatMask]; } private int getBit(int value, int nBit) { return (value >> nBit) & 1; } private int clearBit(int value, int nBit) { return value & ~(1 << nBit); } } |
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