Created
February 4, 2013 04:29
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/* | |
* Problem 50 - Project Euler | |
* Sean Lee 02/03/12 | |
*/ | |
var isPrime = [] | |
var primes = [] | |
var genprimes = function(upperbound){ //Sieve of Erastothenes | |
for (var i = 0; i< upperbound; i++){ | |
isPrime.push(1); | |
} | |
isPrime[0] = 0; | |
isPrime[1] = 0; | |
var i = 2; | |
var loopbound = Math.sqrt(upperbound); | |
while( i <= loopbound){ | |
for( var k = 2*i; k < upperbound; k = k + i){ | |
isPrime[k] = 0; | |
} | |
i++; | |
} | |
for ( var i = 2; i < upperbound; i ++){ | |
if(isPrime[i] === 1) primes.push(i); | |
} | |
} | |
function find(upperbound){ | |
var sums = [] | |
var longest = [0,0]; | |
var i = 0; | |
while (true){ | |
for( var a in sums){ | |
sums[a] += primes[i]; | |
if (sums[a] > upperbound) return longest; | |
if (isPrime[sums[a]]){ | |
var length = sums.length + 1 - a; | |
if (length > longest[1]){ | |
longest = [sums[a], length]; | |
} | |
} | |
} | |
sums.push(primes[i]); | |
i++; | |
} | |
} | |
genprimes(1000000); | |
console.log(find(1000000)[0]); |
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