38 lines
865 B
Plaintext
38 lines
865 B
Plaintext
use num_bigint::BigInt;
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fn main() {
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calc_pi();
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}
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fn calc_pi() {
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let mut q = BigInt::from(1);
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let mut r = BigInt::from(0);
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let mut t = BigInt::from(1);
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let mut k = BigInt::from(1);
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let mut n = BigInt::from(3);
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let mut l = BigInt::from(3);
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let mut first = true;
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loop {
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if &q * 4 + &r - &t < &n * &t {
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print!("{}", n);
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if first {
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print!(".");
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first = false;
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}
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let nr = (&r - &n * &t) * 10;
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n = (&q * 3 + &r) * 10 / &t - &n * 10;
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q *= 10;
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r = nr;
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} else {
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let nr = (&q * 2 + &r) * &l;
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let nn = (&q * &k * 7 + 2 + &r * &l) / (&t * &l);
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q *= &k;
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t *= &l;
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l += 2;
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k += 1;
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n = nn;
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r = nr;
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}
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}
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}
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