Golang | Leetcode Golang题解之第307题区域和检索-数组可修改

题目：

题解：

type NumArray struct {nums, tree []int
}func Constructor(nums []int) NumArray {tree := make([]int, len(nums)+1)na := NumArray{nums, tree}for i, num := range nums {na.add(i+1, num)}return na
}func (na *NumArray) add(index, val int) {for ; index < len(na.tree); index += index & -index {na.tree[index] += val}
}func (na *NumArray) prefixSum(index int) (sum int) {for ; index > 0; index &= index - 1 {sum += na.tree[index]}return
}func (na *NumArray) Update(index, val int) {na.add(index+1, val-na.nums[index])na.nums[index] = val
}func (na *NumArray) SumRange(left, right int) int {return na.prefixSum(right+1) - na.prefixSum(left)
}