100 lines
2.2 KiB
Java
100 lines
2.2 KiB
Java
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public class DominoFill {
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/**
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* .....
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* ..234
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* 01
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*/
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public static int method1(int R, int C) {
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int[] prev = new int[1 << C];
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prev[(1 << C) - 1] = 1;
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for (int r = 0; r < R; r++) {
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for (int c = 0; c < C; c++) {
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int[] cur = new int[1 << C];
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for (int mask = 0; mask < 1 << C; mask++) {
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if ((mask & (1 << c)) != 0) {
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cur[mask ^ (1 << c)] += prev[mask]; // do nothing
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if (c > 0 && (mask & (1 << (c - 1))) == 0) {
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cur[mask | (1 << (c - 1))] += prev[mask]; // horizontal
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}
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} else {
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cur[mask | (1 << c)] += prev[mask]; // vertical
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}
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}
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prev = cur;
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}
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}
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return prev[(1 << C) - 1];
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}
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/**
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* .....
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* ..012
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* 34
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*/
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public static int method2(int R, int C) {
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int[] prev = new int[1 << C];
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prev[(1 << C) - 1] = 1;
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for (int r = 0; r < R; r++) {
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for (int c = 0; c < C; c++) {
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int[] cur = new int[1 << C];
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for (int mask = 0; mask < 1 << C; mask++) {
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int nmask = (mask << 1) & ((1 << C) - 1);
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if ((mask & (1 << (C - 1))) != 0) {
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cur[nmask] += prev[mask]; // do nothing
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if (c > 0 && ((mask & 1) == 0)) {
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cur[nmask | 3] += prev[mask]; // horizontal
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}
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} else {
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cur[nmask | 1] += prev[mask]; // vertical
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}
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}
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prev = cur;
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}
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}
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return prev[(1 << C) - 1];
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}
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// random test
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public static void main(String[] args) {
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for (int r = 1; r < 10; r++) {
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for (int c = 1; c < 10; c++) {
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int res1 = method1(r, c);
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int res2 = method2(r, c);
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if (res1 != res2)
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throw new RuntimeException();
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}
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}
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}
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public static int method0(int R, int C) {
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int[][][] dp = new int[R + 1][C][1 << C];
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dp[0][C - 1][(1 << C) - 1] = 1;
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for (int r = 1; r <= R; r++) {
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for (int c = 0; c < C; c++) {
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int[] prev = c > 0 ? dp[r][c - 1] : dp[r - 1][C - 1];
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for (int mask = 0; mask < 1 << C; mask++) {
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if ((mask & (1 << c)) != 0) {
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dp[r][c][mask ^ (1 << c)] += prev[mask]; // do nothing
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if (c > 0 && (mask & (1 << (c - 1))) == 0) {
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dp[r][c][mask | (1 << (c - 1))] += prev[mask]; // horizontal
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}
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} else {
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dp[r][c][mask | (1 << c)] += prev[mask]; // vertical
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}
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}
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}
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}
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return dp[R][C - 1][(1 << C) - 1];
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}
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}
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