/
ch-2.js
executable file
·70 lines (63 loc) · 1.39 KB
/
ch-2.js
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#! /usr/bin/node
"use strict"
function genprimes(mx) {
let primesh=new Set;
for (let i = 2; i <= Math.min(3, mx); i++) {
primesh.add(i);
}
for (let i = 6; i <= mx; i += 6) {
for (let j = i-1; j <= i+1; j += 2) {
if (j <= mx) {
primesh.add(j);
}
}
}
let q=[2,3,5,7];
let p=q.shift();
let mr=Math.floor(Math.sqrt(mx));
while (p <= mr) {
if (primesh.has(p)) {
let i=p*p
for (let i=p*p; i <= mx; i += p) {
primesh.delete(i);
}
}
if (q.length < 2) {
q.push(q[q.length-1]+4);
q.push(q[q.length-1]+2);
}
p=q.shift();
}
let primes=[...primesh];
primes.sort(function(a,b) {
return a-b;
});
return primes;
}
function primecount(l) {
return genprimes(l - 1).length;
}
if (primecount(10) == 4) {
process.stdout.write("Pass");
} else {
process.stdout.write("FAIL");
}
process.stdout.write(" ");
if (primecount(15) == 6) {
process.stdout.write("Pass");
} else {
process.stdout.write("FAIL");
}
process.stdout.write(" ");
if (primecount(1) == 0) {
process.stdout.write("Pass");
} else {
process.stdout.write("FAIL");
}
process.stdout.write(" ");
if (primecount(25) == 9) {
process.stdout.write("Pass");
} else {
process.stdout.write("FAIL");
}
process.stdout.write("\n");