AlgorithmsJavaScript/Project-Euler/Problem015.js at master · william-queant/AlgorithmsJavaScript · GitHub

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// https://projecteuler.net/problem=15

/* Starting in the top left corner of a 2×2 grid, and only being able to move to

the right and down, there are exactly 6 routes to the bottom right corner.

How many such routes are there through a 20×20 grid?

// A lattice path is composed of horizontal and vertical lines that pass through lattice points.

export const latticePath = (gridSize) => {

let paths

for (let i = 1, paths = 1; i <= gridSize; i++) {

paths = (paths * (gridSize + i)) / i

}

// The total number of paths can be found using the binomial coefficient (b+a)/a.

return paths

}

// > latticePath(20))

// 137846528820

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