langs a-z

Task/Happy-numbers/Pascal/happy-numbers.pascal

@@ -0,0 +1,61 @@
+Program HappyNumbers (output);
+
+uses
+  Math;
+
+function find(n: integer; cache: array of integer): boolean;
+  var
+    i: integer;
+  begin
+    find := false;
+    for i := low(cache) to high(cache) do
+      if cache[i] = n then
+        find := true;
+  end;
+
+function is_happy(n: integer): boolean;
+  var
+    cache: array of integer;
+    sum: integer;
+  begin
+    setlength(cache, 1);
+    repeat
+      sum := 0;
+      while n > 0 do
+      begin
+        sum := sum + (n mod 10)**2;
+        n := n div 10;
+      end;
+      if sum = 1 then
+      begin
+        is_happy := true;
+        break;
+      end;
+      if find(sum, cache) then
+      begin
+        is_happy := false;
+        break;
+      end;
+      n := sum;
+      cache[high(cache)]:= sum;
+      setlength(cache, length(cache)+1);
+    until false;
+  end;
+
+var
+  n, count: integer;
+
+begin
+  n := 1;
+  count := 0;
+  while count < 8 do
+  begin
+    if is_happy(n) then
+    begin
+      inc(count);
+      write(n, ' ');
+    end;
+    inc(n);
+  end;
+  writeln;
+end.