Hailstone sequence: Difference between revisions
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The hailstone sequence has length 112 |
The hailstone sequence has length 112 |
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77031 has the longest sequence of 351 |
77031 has the longest sequence of 351 |
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</pre> |
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==={{header|PL/I-80}}=== |
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<lang PL/I>hailstone_demo: proc options (main); |
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%replace |
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true by '1'b, |
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false by '0'b; |
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dcl |
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(slen, longest) fixed bin(15), |
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(n, n_longest,limit) fixed decimal(12), |
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answer char(1); |
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put skip list ('Display hailstone sequence for what number? '); |
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get list (n); |
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slen = hailstone(n, true); |
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put skip list ('Sequence length = ', slen); |
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put skip(2) list ('Search for longest sequence (y/n)? '); |
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get list (answer); |
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if ((answer ^= 'y') & (answer ^= 'Y')) then stop; |
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put list ('Search to what limit? '); |
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get list (limit); |
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longest = 1; |
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n = 2; |
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do while (n < limit); |
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slen = hailstone(n, false); |
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if slen > longest then |
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do; |
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longest = slen; |
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n_longest = n; |
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end; |
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n = n + 1; |
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end; |
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put skip edit ('Longest sequence =',longest,' for n =',n_longest) |
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(a,f(4),a,f(6)); |
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/* compute, and optionally display, hailstone sequence for n */ |
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hailstone: |
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procedure(n, show) returns (fixed binary); |
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dcl |
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(len, col) fixed binary, |
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(n, k) fixed decimal(12), |
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show bit(1); |
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/* make local copy since n is passed by reference */ |
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k = n; |
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col = 1; |
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len = 1; |
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do while ((k ^= 1) & (k > 0)); |
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if (show) then /* print 8 columns across */ |
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do; |
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put edit (k) (f(8)); |
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col = col + 1; |
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if col > 8 then |
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do; |
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put skip; |
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col = 1; |
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end; |
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end; |
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if (mod(k,2) = 0) then |
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k = k / 2; |
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else |
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k = k * 3 + 1; |
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len = len + 1; |
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end; |
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if (show) then put edit (k) (f(8)); |
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return (len); |
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end hailstone; |
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end hailstone_demo; |
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</lang> |
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{{out}} |
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<pre>Display hailstone sequence for what number? 27 |
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27 82 41 124 62 31 94 47 |
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142 71 214 107 322 161 484 242 |
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121 364 182 91 274 137 412 206 |
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103 310 155 466 233 700 350 175 |
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526 263 790 395 1186 593 1780 890 |
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445 1136 668 334 167 502 251 754 |
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377 1132 566 283 850 425 1276 638 |
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319 958 479 1438 719 2158 1079 3238 |
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1619 4858 2429 7288 3644 1822 911 2734 |
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1367 4102 2051 6154 3077 9232 4616 2308 |
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1154 577 1732 866 433 1300 650 325 |
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976 488 244 122 61 184 92 46 |
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23 70 35 106 53 160 80 40 |
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20 10 5 16 8 4 2 1 |
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Sequence length = 112 |
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Search for longest sequence (y/n)? y |
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Search to what limit? 100000 |
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Longest sequence = 351 for n = 77031 |
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</pre> |
</pre> |
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