Taxicab numbers: Difference between revisions
→{{header|ZX Spectrum Basic}}: added a second program that produces the first 25 taxicab numbers.
(Added Befunge example.) |
(→{{header|ZX Spectrum Basic}}: added a second program that produces the first 25 taxicab numbers.) |
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10:65728=31^3+33^3=12^3+40^3
D BREAK into program, 100:1</pre>
This program produces the first 25 Taxicab numbers. It is written with speed in mind.
The runtime is about 45 minutes on a ZX Spectrum (3.5 Mhz).
<lang zxbasic> 10 LET T=0: DIM F(72): LET D=0: LET S=0: LET B=0: LET A=0: LET C=0
20 DIM H(50): DIM Y(50,2): FOR D=1 TO 72: LET F(D)=D*D*D: NEXT D
30 FOR A=1 TO 58: FOR B=A+1 TO 72: LET S=F(A)+F(B): FOR D=B-1 TO A STEP -1
40 LET T=S-F(D): IF T>F(D) THEN NEXT B: NEXT A: GO TO 90
45 IF s>405224 THEN GO TO 70
50 IF F(INT (EXP (LN (T)/3)+.5))=T THEN GO TO 80
60 NEXT D
70 NEXT B: NEXT A: GO TO 90
80 PRINT S,: LET C=C+1: LET H(C)=S: LET Y(C,1)=A*65536+B: LET Y(C,2)=INT (EXP (LN (T)/3)+.5)*65536+D: GO TO 70
90 LET S=INT (C/2)
100 LET T=0: FOR A=1 TO C-S: IF H(A)>H(A+S) THEN LET T=H(A): LET H(A)=H(A+S): LET H(A+S)=T: LET T=Y(A,1): LET Y(A,1)=Y(A+S,1): LET Y(A+S,1)=T: LET T=Y(A,2): LET Y(A,2)=Y(A+S,2): LET Y(A+S,2)=T
110 NEXT A: IF T<>0 THEN GO TO 100
120 IF S<>1 THEN LET S=INT (S/2): GO TO 100
130 CLS : FOR A=1 TO 25: PRINT A;":";H(A);"=";
131 LPRINT A;":";H(A);"=";:
140 LET T=INT (Y(A,1)/65536): PRINT T;"^3+";Y(A,1)-T*65536;"^3=";
141 LPRINT T;"^3+";Y(A,1)-T*65536;"^3=";
150 LET T=INT (Y(A,2)/65536): PRINT T;"^3+";Y(A,2)-T*65536;"^3"
151 LPRINT T;"^3+";Y(A,2)-T*65536;"^3"
160 NEXT A: PRINT
170 STOP</lang>
{{out}}
<pre>1:1729=1^3+12^3=9^3+10^3
2:4104=2^3+16^3=9^3+15^3
3:13832=2^3+24^3=18^3+20^3
4:20683=10^3+27^3=19^3+24^3
5:32832=4^3+32^3=18^3+30^3
6:39312=2^3+34^3=15^3+33^3
7:40033=9^3+34^3=16^3+33^3
8:46683=3^3+36^3=27^3+30^3
9:64232=17^3+39^3=26^3+36^3
10:65728=12^3+40^3=31^3+33^3
11:110656=4^3+48^3=36^3+40^3
12:110808=6^3+48^3=27^3+45^3
13:134379=12^3+51^3=38^3+43^3
14:149389=8^3+53^3=29^3+50^3
15:165464=20^3+54^3=38^3+48^3
16:171288=17^3+55^3=24^3+54^3
17:195841=9^3+58^3=22^3+57^3
18:216027=3^3+60^3=22^3+59^3
19:216125=5^3+60^3=45^3+50^3
20:262656=8^3+64^3=36^3+60^3
21:314496=4^3+68^3=30^3+66^3
22:320264=18^3+68^3=32^3+66^3
23:327763=30^3+67^3=51^3+58^3
24:373464=6^3+72^3=54^3+60^3
25:402597=42^3+69^3=56^3+61^3</pre>
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