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307 solved #71
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88 changes: 88 additions & 0 deletions
src/0307_Range_Sum_Query_Mutable/range_sum_query_mut.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,88 @@ | ||
| /* | ||
| 307. Range Sum Query - Mutable | ||
| https://leetcode.com/problems/range-sum-query-mutable/ | ||
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| Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. | ||
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| The update(i, val) function modifies nums by updating the element at index i to val. | ||
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| Note: | ||
| The array is only modifiable by the update function. | ||
| You may assume the number of calls to update and sumRange function is distributed evenly. | ||
| */ | ||
| // time: 2019年01月29日 | ||
| // 线段树时间复杂度为:O(log n) | ||
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| package rsqm | ||
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| // NumArray 线段树 | ||
| type NumArray struct { | ||
| segmentTree []int | ||
| data []int | ||
| } | ||
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| // Constructor 线段树生成函数 | ||
| func Constructor(nums []int) NumArray { | ||
| na := NumArray{segmentTree: make([]int, len(nums)*4), data: nums[:]} | ||
| na.buildSegmentTree(0, 0, len(na.data)-1) | ||
| return na | ||
| } | ||
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| func (na *NumArray) buildSegmentTree(treeIndex, left, right int) { | ||
| // 线段树处理的数据不能为空。 | ||
| //if right < left { | ||
| // return | ||
| //} | ||
| if left == right { | ||
| na.segmentTree[treeIndex] = na.data[left] | ||
| return | ||
| } | ||
| mid := left + (right-left)>>1 | ||
| leftTreeIndex := 2*treeIndex + 1 | ||
| rightTreeIndex := 2*treeIndex + 2 | ||
| na.buildSegmentTree(leftTreeIndex, left, mid) | ||
| na.buildSegmentTree(rightTreeIndex, mid+1, right) | ||
| na.segmentTree[treeIndex] = na.segmentTree[leftTreeIndex] + na.segmentTree[rightTreeIndex] | ||
| } | ||
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| // Update 线段树更新操作。 | ||
| func (na *NumArray) Update(i int, val int) { | ||
| na.setter(0, 0, len(na.data)-1, i, val) | ||
| } | ||
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| func (na *NumArray) setter(treeIndex, left, right, index, val int) { | ||
| if left == right { | ||
| na.segmentTree[treeIndex] = val | ||
| return | ||
| } | ||
| mid := left + (right-left)>>1 | ||
| leftTreeIndex := 2*treeIndex + 1 | ||
| rightTreeIndex := 2*treeIndex + 2 | ||
| if index >= mid+1 { | ||
| na.setter(rightTreeIndex, mid+1, right, index, val) | ||
| } else { | ||
| na.setter(leftTreeIndex, left, mid, index, val) | ||
| } | ||
| na.segmentTree[treeIndex] = na.segmentTree[leftTreeIndex] + na.segmentTree[rightTreeIndex] | ||
| } | ||
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| // SumRange 线段树查询 | ||
| func (na *NumArray) SumRange(i int, j int) int { | ||
| return na.query(0, 0, len(na.data)-1, i, j) | ||
| } | ||
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| func (na *NumArray) query(treeIndex, left, right, queryL, queryR int) int { | ||
| if left == queryL && right == queryR { | ||
| return na.segmentTree[treeIndex] | ||
| } | ||
| mid := left + (right-left)>>1 | ||
| leftTreeIndex := 2*treeIndex + 1 | ||
| rightTreeIndex := 2*treeIndex + 2 | ||
| if queryL >= mid+1 { | ||
| return na.query(rightTreeIndex, mid+1, right, queryL, queryR) | ||
| } else if queryR <= mid { | ||
| return na.query(leftTreeIndex, left, mid, queryL, queryR) | ||
| } else { | ||
| return na.query(leftTreeIndex, left, mid, queryL, mid) + na.query(rightTreeIndex, mid+1, right, mid+1, queryR) | ||
| } | ||
| } |
15 changes: 15 additions & 0 deletions
src/0307_Range_Sum_Query_Mutable/range_sum_query_mut_test.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,15 @@ | ||
| package rsqm | ||
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| import "testing" | ||
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| func TestNumArray(t *testing.T) { | ||
| nums := []int{1, 2, 3, 6, 7, 8, 9, 3, 4, 2, 5} | ||
| na := Constructor(nums) | ||
| if res := na.SumRange(4, 9); res != 33 { | ||
| t.Errorf("expected %d, got %d", 43, res) | ||
| } | ||
| na.Update(6, 10) | ||
| if res := na.SumRange(4, 9); res != 34 { | ||
| t.Errorf("expected %d, got %d", 44, res) | ||
| } | ||
| } |
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