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PascalsTriangle.swift
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PascalsTriangle.swift
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//
// PascalsTriangle.swift
// LeetCode
//
// Created by 榛庤档澶儙 on 15/02/2018.
// Copyright 漏 2018 lizhaotailang. All rights reserved.
//
// Given numRows, generate the first numRows of Pascal's triangle.
//
// For example, given numRows = 5,
// Return
//
// [
// [1],
// [1,1],
// [1,2,1],
// [1,3,3,1],
// [1,4,6,4,1]
// ]
//
// Accepted. See [PascalsTriangleTests](./LeetCodeTests/PascalsTriangleTests.swift) for test cases.
//
import Foundation
class PascalsTriangle {
func generate(_ numRows: Int) -> [[Int]] {
var results = Array<Array<Int>>.init()
if numRows == 0 {
return results
}
if numRows == 1 {
results.append([1])
return results
}
if numRows == 2 {
results.append([1])
results.append([1, 1])
return results
}
var tmp = self.generate(numRows - 1)
var list = Array<Int>.init(repeating: 1, count: numRows)
let last = tmp[tmp.count - 1]
for i in 1..<last.count {
list[i] = last[i - 1] + last[i]
}
tmp.append(list)
return tmp
}
}