├── README.md
├── SeedFinder.java
└── out.txt


/README.md:
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 1 | # minecraft-diagonal-seed-finder
 2 | Finds Minecraft 1.15 seeds which make the decorations in nearby chunks repeat.
 3 | You can find more information [on Matthew's youtube channel](https://www.youtube.com/watch?v=UtNXUMrSIxQ).
 4 | 
 5 | ## Building and Running
 6 | As this code is just a single `.java` file, you should be able to build with this line.
 7 | ```sh
 8 | $ javac SeedFinder.java
 9 | ```
10 | You can run it with this line.
11 | ```sh
12 | $ java SeedFinder > out.txt
13 | ```
14 | This should produce the output in a file called `out.txt`.
15 | 
16 | The output file is also already precomputed and included in the repository, in case you just want the seeds without running the code.
17 | 
18 | ## Output Format
19 | Each line of the output has a seed, then the direction that the seed's decorator repeats. Due to the way the code searches for seeds, the only directions produced will be `-1 1` and `1 1`.
20 | 
21 | Because of the way minecraft seeds the game, all seeds that have the same least significant 48 bits have the same decorator behavior. This code only outputs seeds from 0 <= x < 2^48, so if you need more seeds with the same decorator properties, you can use other 64 bit numbers that have the same least significant 64 bits as any of the seeds in `out.txt`.
22 | 


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/SeedFinder.java:
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 1 | import java.util.Random;
 2 | public class SeedFinder {
 3 |     public static void main (String[] args) {
 4 |         long mask = (1L <<31)-1;
 5 |         for (long i = 0; i < 2*65536; i++) {
 6 |             long b = ((205749139540585L*i + 277363943098L) >> 17) & mask;
 7 |             // case where 8u = 201793413  * -b
 8 |             if ((b & 7) == 0) {
 9 |                 long u = ((201793413 * -b) & mask) >> 3;
10 |                 for (long j = 0; j < 8; j++) {
11 |                     convertToSeed(i, u + (j << 28));
12 |                 }
13 |             }
14 |             // case where 2u = 606856477 * (-b -1)
15 |             else if ((b & 1) == 1) {
16 |                 long u = ((606856477 * (-b -1)) & mask) >> 1;
17 |                 convertToSeed(i, u);
18 |                 convertToSeed(i, u + (1 << 30));
19 |             }
20 |         }//50780870847 11622054337284
21 |     }
22 |     public static void convertToSeed(long i, long u) {
23 |         int blocks = 16;
24 |         long seed = (u << 17) + i;
25 |         seed = 254681119335897L * seed + 120305458776662L;
26 |         seed ^= 0x5deece66dL;
27 |         seed &= ((1L << 48)-1);
28 |         Random r = new Random(seed);
29 |         long a = r.nextLong() | 1;
30 |         long b = r.nextLong() | 1;
31 |         if (((blocks*a+blocks*b) & ((1L << 48)-1))==0) {
32 |             System.out.println(seed + " 1 1");
33 |         } else if (((blocks*a-blocks*b) & ((1L << 48)-1))==0) {
34 |             System.out.println(seed + " -1 1");
35 |         }
36 |     }
37 | }


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/out.txt:
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 1 | 102496288339226 1 1
 2 | 243233776694554 1 1
 3 | 25503018638468 1 1
 4 | 166240506993796 1 1
 5 | 194863804823673 1 1
 6 | 54126316468345 1 1
 7 | 180285425070967 1 1
 8 | 39547936715639 1 1
 9 | 229379390903807 1 1
10 | 88641902548479 1 1
11 | 11631417851241 1 1
12 | 152368906206569 1 1
13 | 278457215087719 1 1
14 | 137719726732391 1 1
15 | 74811678275130 -1 1
16 | 109996050363962 -1 1
17 | 145180422452794 -1 1
18 | 180364794541626 -1 1
19 | 215549166630458 -1 1
20 | 250733538719290 -1 1
21 | 4442934097466 -1 1
22 | 39627306186298 -1 1
23 | 60743603216145 1 1
24 | 201481091571473 1 1
25 | 74753121498560 1 1
26 | 215490609853888 1 1
27 | 225951381575532 -1 1
28 | 261135753664364 -1 1
29 | 14845149042540 -1 1
30 | 50029521131372 -1 1
31 | 85213893220204 -1 1
32 | 120398265309036 -1 1
33 | 155582637397868 -1 1
34 | 190767009486700 -1 1
35 | 123866381128776 1 1
36 | 264603869484104 1 1
37 | 187592346697722 1 1
38 | 46854858342394 1 1
39 | 172961353594608 1 1
40 | 32223865239280 1 1
41 | 60829983200677 1 1
42 | 201567471556005 1 1
43 | 236703458319970 1 1
44 | 95965969964642 1 1
45 | 43099331928968 -1 1
46 | 78283704017800 -1 1
47 | 113468076106632 -1 1
48 | 148652448195464 -1 1
49 | 183836820284296 -1 1
50 | 219021192373128 -1 1
51 | 254205564461960 -1 1
52 | 7914959840136 -1 1
53 | 194239033000162 -1 1
54 | 229423405088994 -1 1
55 | 264607777177826 -1 1
56 | 18317172556002 -1 1
57 | 53501544644834 -1 1
58 | 88685916733666 -1 1
59 | 123870288822498 -1 1
60 | 159054660911330 -1 1
61 | 159072574510805 1 1
62 | 18335086155477 1 1
63 | 82025653894727 1 1
64 | 222763142250055 1 1


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