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303. Range Sum Query - Immutable #20

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Merged
zwfang merged 1 commit into master from range-sum-query-immutable
Dec 28, 2018
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1 change: 1 addition & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ continually updating 😃.
* [215. Kth Largest Element in an Array](./src/0215_kth_largest_element_in_an_array/kthleiaa.go)   *`sort`*
* [283. Move Zeroes(solution1)](./src/0283_move_zeroes/move_zeroes.go)   *`sliding window`*
* [283. Move Zeroes(solution2)](./src/0283_move_zeroes/move_zeroes2.go)   *`sliding window`*
* [303. Range Sum Query - Immutable](src/0303_range_sum_query/rsqim.go)
* [349. Intersection of Two Arrays](./src/0349_intersection_of_2_arrays/intersection_of_two_arrays.go)   *`set`*
* [350. Intersection of Two Arrays II](./src/0350_intersection_of_two_arrays2/intersection_of_two_arrays2.go)   *`hash table`*
* [447. Number of Boomerangs](./src/0447_number_of_boomerangs/number_of_boomerangs.go)   *`hash table`*
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30 changes: 30 additions & 0 deletions src/0303_range_sum_query/rsqim.go
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/*
303. Range Sum Query - Immutable
https://leetcode.com/problems/range-sum-query-immutable/

Given an integer array nums,
find the sum of the elements between indices i and j (i ≤ j), inclusive.
*/
// time: 2018年12月28日

package rsqim

// NumArray store sum of nums sub-list.
type NumArray struct {
sum []int
}

// Constructor make NumArray instance.
func Constructor(nums []int) NumArray {
nA := NumArray{sum: make([]int, 1)}
for _, num := range nums {
nA.sum = append(nA.sum, nA.sum[len(nA.sum)-1]+num)
}
return nA
}

// SumRange find the sum of the elements between indices i and j(i <= j), inclusive.
func (na *NumArray) SumRange(i int, j int) int {
j++
return na.sum[j] - na.sum[i]
}
22 changes: 22 additions & 0 deletions src/0303_range_sum_query/rsqim_test.go
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package rsqim

import "testing"

func TestSumRange(t *testing.T) {
nums := []int{-2, 0, 3, -5, 2, -1}
ranges := [][]int{
{0, 2},
{2, 5},
{0, 5},
}

expected := []int{1, -1, -3}

obj := Constructor(nums)

for index, section := range ranges {
if res := obj.SumRange(section[0], section[1]); res != expected[index] {
t.Errorf("expected %d, got %d", expected[index], res)
}
}
}
1 change: 1 addition & 0 deletions src/README.md
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Expand Up @@ -40,6 +40,7 @@
|0226|[Invert Binary Tree](./0226_invert_binary_tree/invert_binary_tree.go)|Easy|*`recursion; `* *`binary tree`*|
|0283|[Move Zeroes(solution1)](./0283_move_zeroes/move_zeroes.go) <br/> [Move Zeroes(solution2)](./0283_move_zeroes/move_zeroes2.go)|Easy|*`array`*|
|0300|[Longest Increasing Subsequence](./0300_longest_increasing_subsequence/lis.go)|Medium|*`dp`*|
|0303|[303. Range Sum Query - Immutable](0303_range_sum_query/rsqim.go)|Easy||
|0343|[Integer Break](./0343_integer_break/integer_break.go)|Medium|*`recursion;`* *`memory search;`* *`dynamic programming`*|
|0344|[344. Reverse String](0344_reverse_string/reverse_string.go)|Easy|*`double index`*|
|0345|[345. Reverse Vowels of a String](0345_reverse_vowels_of_a_string/reverse_vowels.go)|Easy|*`double index`*|
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