added problem 119

Author: SHA65536

problems/problem0119/pascal_ii.go

@@ -0,0 +1,31 @@
+package problem0119
+
+/*
+Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle.
+In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:
+*/
+
+func getRow(rowIndex int) []int {
+	if rowIndex == 0 {
+		return []int{1}
+	} else if rowIndex == 1 {
+		return []int{1, 1}
+	}
+
+	var cur = make([]int, 1, rowIndex+1)
+	var prev = make([]int, 2, rowIndex+1)
+	cur[0] = 1
+	prev[0] = 1
+	prev[1] = 1
+
+	for i := 2; i <= rowIndex+1; i++ {
+		cur = cur[:i]
+		cur[0] = 1
+		for j := 1; j < len(cur)-1; j++ {
+			cur[j] = prev[j-1] + prev[j]
+		}
+		cur[len(cur)-1] = 1
+		prev, cur = cur, prev
+	}
+	return prev
+}

problems/problem0119/pascal_ii_test.go

@@ -0,0 +1,39 @@
+package problem0119
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type TestCase struct {
+	Input    int
+	Expected []int
+}
+
+var TestCases = []TestCase{
+	{3, []int{1, 3, 3, 1}},
+	{0, []int{1}},
+	{1, []int{1, 1}},
+	{10, []int{1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1}},
+	{33, []int{1, 33, 528, 5456, 40920, 237336, 1107568, 4272048, 13884156, 38567100, 92561040, 193536720, 354817320, 573166440, 818809200, 1037158320, 1166803110, 1166803110, 1037158320, 818809200, 573166440, 354817320, 193536720, 92561040, 38567100, 13884156, 4272048, 1107568, 237336, 40920, 5456, 528, 33, 1}},
+}
+
+func TestGetPascalRowII(t *testing.T) {
+	assert := assert.New(t)
+
+	for _, tc := range TestCases {
+		want := tc.Expected
+		got := getRow(tc.Input)
+		assert.Equal(want, got, fmt.Sprintf("%+v", tc))
+	}
+}
+
+func BenchmarkGetPascalRowII(b *testing.B) {
+	for _, tc := range TestCases {
+		for i := 0; i < b.N; i++ {
+			getRow(tc.Input)
+		}
+	}
+}

readme.md

@@ -106,6 +106,7 @@ Each problem is in it's own directory, with test files. There are helper package
 | 0116 | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node) | [My Solution](./problems/problem0116) | ✅ |
 | 0117 | [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii) | [My Solution](./problems/problem0117) | ✅ |
 | 0118 | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle) | [My Solution](./problems/problem0118) | ✅ |
+| 0119 | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii) | [My Solution](./problems/problem0119) | ✅ |
 | 0120 | [Triangle](https://leetcode.com/problems/triangle) | [My Solution](./problems/problem0120) | ✅ |
 | 0121 | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock) | [My Solution](./problems/problem0121) | ✅ | 
 | 0122 | [Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii) | [My Solution](./problems/problem0122) | ✅ |