problem700.ijs


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findCoins =: {{
	NB. The distance from the start (0) either always increases, or we find a coin.
	NB. This means we can calculate the new distance or next coin as y|lastCoin+offset
	NB. If this value is less than the last coin, we have a new coin.
	NB. If the value is larger than the last offset, we cannot have a new coin, so
	NB. we increase the offset.
	lastCoin =. x
	offset =. x
	coins =. lastCoin
	while. lastCoin > 1 do.
		tmpOffset =. y|lastCoin + offset
		if. tmpOffset > offset do.
			offset =. tmpOffset
		elseif. tmpOffset < lastCoin do.
			lastCoin =. tmpOffset
			coins =. coins,lastCoin
		end.
	end.
	coins
}}

problem700 =: +/ 1504170715041707 findCoins 4503599627370517