project euler

Author: coderxiang

ProjectEuler/gen_prime.ml

@@ -1,12 +1,11 @@
 open Hashtbl
 
-let get_seq ?(x = 1) ?(inc = 1) n = 
+let range ?(x = 1) ?(inc = 1) n = 
   let rec aux acc x = 
 	if x > n then acc else aux (x :: acc) (x + inc)
   in
   List.rev (aux [] x)
 
-
 let gen_prime n = 
   let update x step lst = 
 	let rec aux acc cur y = 
@@ -28,9 +27,14 @@ let gen_prime n =
 		else aux (x :: acc) (update (x*x) x xs)
 	  end
   in
-  aux [] (List.tl (get_seq n))
+  aux [] (List.tl (range n))
 
 
 let pm_list = gen_prime 100000
 let pm_tb = Hashtbl.create (List.length pm_list) 
 let () = List.iter (fun x -> Hashtbl.add pm_tb x true) pm_list
+
+let ( |> ) v f = f v
+let ( <| ) f v = f v
+let foi = float_of_int
+let iof = int_of_float

ProjectEuler/p053.rb

@@ -0,0 +1,16 @@
+ans = 0;
+c = Array.new(101) {Array.new(101)}
+c[0][0] = 1;
+(1..100).each{|i| 
+  c[i][0] = 1; c[i][i] = 1;
+  (1..i-1).each {|j|
+    if c[i-1][j-1] == -1 || c[i-1][j] == -1 || c[i-1][j-1] + c[i-1][j] > 1000000 
+      c[i][j] = -1;
+      ans += 1;
+    else
+      c[i][j] = c[i-1][j-1] + c[i-1][j]
+    end
+  }
+}
+p ans
+

ProjectEuler/p068.cpp

@@ -0,0 +1,69 @@
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+#include <string>
+#include <iostream>
+#include <cstdlib>
+#include <sstream>
+
+using namespace std;
+
+int a[11];
+bool flag[11];
+string ans;
+int idx[15] = {1,6,7,2,7,8,3,8,9,4,9,10,5,10,6};
+int b[7] = {0, 6, 7, 1, 2, 3, 4};
+
+string trans () {
+	stringstream ret;
+	for (int i = 0; i < 15; ++i)
+		ret << a[idx[i]];
+	return ret.str();
+}
+
+bool chk () {
+	int i, j, k;
+	k = a[1] + a[6] + a[7];
+	bool flag1[11];
+	memcpy(flag1, flag, sizeof (flag));
+	
+	j = a[8] = k - a[2] - a[7];
+	if(j < 1 || j > 10 || flag1[j]) return false; else flag1[j] = true;
+	
+	j = a[9] = k - a[3] - a[8];
+	if(j < 1 || j > 10 || flag1[j]) return false; else flag1[j] = true;
+	
+	j = a[10] = k - a[4] - a[9];
+	if(j < 1 || j > 10 || flag1[j]) return false; else flag1[j] = true;
+	
+	j = a[5] = k - a[6] - a[10];
+	if(j < 1 || j > 10 || flag1[j] || j <= a[1]) return false; else flag1[j] = true;
+	
+	return true;	
+}
+
+void DFS (int n, int x) {
+	int i, j, k;
+	if (n == 7) {
+		if (chk ())
+			ans = max (ans, trans());
+		return;
+	}
+	if (n > 3 && n <= 6 && x <= a[1]) return;
+	flag[a[b[n]] = x] = true;
+	
+	for (i = 1; i <= 10; ++i) {
+		if (flag[i]) continue;
+		DFS (n + 1, i);
+	}
+	flag[x] = false;
+}
+
+int main () {
+	ans = "000000";
+	for (int i = 1; i <= 10; ++i) {
+		memset (flag, false, sizeof(flag));
+		DFS (1, i);
+	}
+	cout << ans << endl;
+}

ProjectEuler/p085.ml

@@ -0,0 +1,20 @@
+let range ?(x = 1) ?(inc = 1) n = 
+  let rec aux acc x = 
+	if x > n then acc else aux (x :: acc) (x + inc)
+  in
+  List.rev (aux [] x)
+
+	
+let g acc x = 
+  List.fold_left (fun acc y ->
+	let cnt = x * (x - 1) * y * (y - 1) / 4 in
+	let diff = abs (cnt - 2000000) in
+	if diff < (List.hd acc) then 
+	  [diff; x; y]
+	else
+	  acc)
+	acc (range ~x:x 100)
+	
+let ret = List.fold_left g [100000; 0; 0] (range ~x:2 100) in
+(List.hd (List.rev ret) - 1) * (List.hd (List.tl ret) - 1)
+

ProjectEuler/p087.ml

@@ -0,0 +1,54 @@
+open Hashtbl
+
+let get_seq ?(x = 1) ?(inc = 1) n = 
+  let rec aux acc x = 
+	if x > n then acc else aux (x :: acc) (x + inc)
+  in
+  List.rev (aux [] x)
+
+
+let gen_prime n = 
+  let update x step lst = 
+	let rec aux acc cur y = 
+	  match y with
+		| [] -> List.rev acc
+		| h :: hs -> begin
+		  if cur < h then aux acc (cur + step) y
+		  else if h < cur then aux (h :: acc) cur hs else aux acc (cur + step) hs
+		end 
+	in
+	aux [] x lst
+  in
+
+  let rec aux acc lst = 
+	match lst with
+	  | [] -> List.rev acc
+	  | x :: xs -> begin
+		if x * x > n then aux (x :: acc) xs
+		else aux (x :: acc) (update (x*x) x xs)
+	  end
+  in
+  aux [] (List.tl (get_seq n))
+
+
+let pm_list = gen_prime 10000
+let tb = Hashtbl.create 5000011
+let arr_2 = Array.of_list (List.filter (fun x -> x * x <= 50000000) pm_list)
+let arr_3 = Array.of_list (List.filter (fun x -> x * x * x <= 50000000) pm_list)
+let arr_4 = Array.of_list (List.filter (fun x -> x * x * x * x <= 50000000) pm_list)
+let n2 = Array.length arr_2
+let n3 = Array.length arr_3
+let n4 = Array.length arr_4
+
+
+for i = 0 to n2-1 do
+  for j = 0 to n3-1 do
+	for k = 0 to n4-1 do
+	  Hashtbl.add tb (arr.(i) * arr.(i) + arr.(j) * arr.(j) * arr.(j) 
+		+ arr.(k) * arr.(k) * arr.(k) * arr.(k)) true
+	done;
+  done;
+done
+  
+let ans = List.fold_left (fun acc x -> if Hashtbl.mem tb x then 1 + acc else acc) 
+  0 (get_seq 50000000)