47, 49, 50

3 files changed, 182 insertions, 0 deletions

diff --git a/euler47.myr b/euler47.myr
new file mode 100644
index 0000000..f53bec0
--- /dev/null
+++ b/euler47.myr
@@ -0,0 +1,49 @@
+use std
+
+const n_prime_factors = {n
+	var nf = 0
+	var p = 3
+
+	if n % 2 == 0
+		while n % 2 == 0
+			n /= 2
+		;;
+		nf = 1
+	;;
+
+	while n > 1
+		if n % p == 0
+			while n % p == 0
+				n /= p
+			;;
+			nf ++
+		;;
+		p += 2;
+	;;
+	-> nf
+}
+
+
+const main = {
+	var i = 210
+	while true
+		if !(n_prime_factors(i) == 4)
+			i++
+			continue
+		;;
+		if !(n_prime_factors(i+1) == 4)
+			i += 2
+			continue
+		;;
+		if !(n_prime_factors(i+2) == 4)
+			i += 3
+			continue
+		;;
+		if !(n_prime_factors(i+3) == 4)
+			i += 4
+			continue
+		;;
+		std.put("{}\n", i)
+		break
+	;;
+}
diff --git a/euler49.myr b/euler49.myr
new file mode 100644
index 0000000..4003767
--- /dev/null
+++ b/euler49.myr
@@ -0,0 +1,53 @@
+use std
+
+const isprime = {n
+	if n == 1 || n % 2 == 0
+		->false
+	;;
+	for var i = 3; i * i <= n; i++
+		if n % i == 0
+			-> false
+		;;
+	;;
+	-> true
+}
+
+const isperm = {a, b
+	var dmap: int[10]
+	for var i = 0; i < 10; i++
+		dmap[i] = 0
+	;;
+	while a > 0
+		dmap[a % 10] ++
+		a /= 10
+	;;
+	while b > 0
+		var t = b % 10
+		dmap[t] --
+		if dmap[t] < 0
+			-> false
+		;;
+		b /= 10
+	;;
+	-> true
+}
+
+const main = {
+	for var i = 1001; i < 9999; i++
+		if !isprime(i)
+			continue
+		;;
+		for var j = 2; i + j * 2 <= 9999; j ++
+			var t1 = i + j
+			var t2 = t1 + j
+			if !isprime(t1) || !isprime(t2)
+				continue
+			;;
+			if !isperm(i, t1) || !isperm(i, t2)
+				continue
+			;;
+			std.put("{} {} {}\n", i, t1, t2)
+		;;
+	;;
+}
+
diff --git a/euler50.myr b/euler50.myr
new file mode 100644
index 0000000..4fd1b07
--- /dev/null
+++ b/euler50.myr
@@ -0,0 +1,80 @@
+use std
+
+var primes: int[100000]
+var nprimes: int
+
+const sieve = {
+	nprimes = 1
+	primes[0] = 2
+
+	for var i = 3; i < 1_000_000; i++
+		for var j = 0; j < nprimes; j++
+			if i % primes[j] == 0
+				break
+			;;
+			if primes[j] * primes[j] > i
+				primes[nprimes] = i
+				nprimes++
+				break
+			;;
+		;;
+	;;
+}
+
+const isprime = {n
+	for var i = 0; i < nprimes; i++
+		if n % primes[i] == 0
+			-> false
+		;;
+		if (primes[i]*primes[i] > n)
+			-> true
+		;;
+	;;
+	-> false
+}
+
+const prime_terms = {n, limit
+	var L = n / limit
+	var i = 0
+	var j = 0
+	var sum = 0
+
+	while primes[i] < L
+		/* calculate a[i..j] */
+		while sum < n
+			sum += primes[j]
+			if sum == n
+				-> j - i + 1
+			;;
+			j++
+		;;
+		/* calculate a[i..j-1] */
+		while sum > n
+			sum -= primes[i]
+			i++
+			if sum == n
+				-> j - i
+			;;
+		;;
+	;;
+	-> 0
+}
+
+const main = {
+	sieve()
+	std.put("{} primes below 1000000\n", nprimes)
+	var maxL = 21
+	var ans = 953
+	for var i = 954; i < 1_000_000; i++
+		if !isprime(i)
+			continue
+		;;
+		var pt = prime_terms(i, maxL)
+		if pt > maxL
+			maxL = pt
+			ans = i
+		;;
+	;;
+	std.put("len = {} ans = {}\n", maxL, ans)
+}
+