DataGrids

void Main() { var input = 29000000; var guess = 0; while(PresentsForHouse(guess) < input) guess += 1000 ; var house = guess; for (var i = 0; i< 50000; i++) if (PresentsForHouse(guess-i) >= input) house = guess-i; house.Dump(); guess = 0; while(PresentsForHouse2(guess) < input) guess += 1000 ; house = guess; for (var i = 0; i< 50000; i++) if (PresentsForHouse2(guess-i) >= input) house = guess-i; house.Dump(); } int PresentsForHouse(int house) { var presents = 0; for(var elf = 1; elf <= house; elf++) if ((house % elf) == 0) presents += (elf * 10); return presents; } int PresentsForHouse2(int house) { var presents = 0; for(var elf = 1; elf <= house; elf++) if ((house % elf) == 0 && (house / elf) <= 50) presents += (elf * 11); return presents; }