给你一个数组 nums
,请你完成两类查询。
- 其中一类查询要求 更新 数组
nums
下标对应的值 - 另一类查询要求返回数组
nums
中索引left
和索引right
之间( 包含 )的nums元素的 和 ,其中left <= right
实现 NumArray
类:
NumArray(int[] nums)
用整数数组nums
初始化对象void update(int index, int val)
将nums[index]
的值 更新 为val
int sumRange(int left, int right)
返回数组nums
中索引left
和索引right
之间( 包含 )的nums元素的 和 (即,nums[left] + nums[left + 1], ..., nums[right]
)
示例 1:
输入: ["NumArray", "sumRange", "update", "sumRange"] [[[1, 3, 5]], [0, 2], [1, 2], [0, 2]] 输出: [null, 9, null, 8] 解释: NumArray numArray = new NumArray([1, 3, 5]); numArray.sumRange(0, 2); // 返回 1 + 3 + 5 = 9 numArray.update(1, 2); // nums = [1,2,5] numArray.sumRange(0, 2); // 返回 1 + 2 + 5 = 8
提示:
1 <= nums.length <= 3 * 104
-100 <= nums[i] <= 100
0 <= index < nums.length
-100 <= val <= 100
0 <= left <= right < nums.length
- 调用
update
和sumRange
方法次数不大于3 * 104
树状数组,也称作“二叉索引树”(Binary Indexed Tree)或 Fenwick 树。 它可以高效地实现如下两个操作:
-
单点更新
$update(x, delta)$ : 把序列$x$ 位置的数加上一个值$delta$ ; -
前缀和查询
$query(x)$ :查询序列$[1,...x]$ 区间的区间和,即位置$x$ 的前缀和。
这两个操作的时间复杂度均为
树状数组最基本的功能就是求比某点
对于本题,我们在构造函数中,先创建一个树状数组,然后遍历数组中每个元素的下标
对于
对于
空间复杂度为
class BinaryIndexedTree:
__slots__ = ["n", "c"]
def __init__(self, n):
self.n = n
self.c = [0] * (n + 1)
def update(self, x: int, delta: int):
while x <= self.n:
self.c[x] += delta
x += x & -x
def query(self, x: int) -> int:
s = 0
while x > 0:
s += self.c[x]
x -= x & -x
return s
class NumArray:
__slots__ = ["tree"]
def __init__(self, nums: List[int]):
self.tree = BinaryIndexedTree(len(nums))
for i, v in enumerate(nums, 1):
self.tree.update(i, v)
def update(self, index: int, val: int) -> None:
prev = self.sumRange(index, index)
self.tree.update(index + 1, val - prev)
def sumRange(self, left: int, right: int) -> int:
return self.tree.query(right + 1) - self.tree.query(left)
# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# obj.update(index,val)
# param_2 = obj.sumRange(left,right)
class BinaryIndexedTree {
private int n;
private int[] c;
public BinaryIndexedTree(int n) {
this.n = n;
c = new int[n + 1];
}
public void update(int x, int delta) {
while (x <= n) {
c[x] += delta;
x += x & -x;
}
}
public int query(int x) {
int s = 0;
while (x > 0) {
s += c[x];
x -= x & -x;
}
return s;
}
}
class NumArray {
private BinaryIndexedTree tree;
public NumArray(int[] nums) {
int n = nums.length;
tree = new BinaryIndexedTree(n);
for (int i = 0; i < n; ++i) {
tree.update(i + 1, nums[i]);
}
}
public void update(int index, int val) {
int prev = sumRange(index, index);
tree.update(index + 1, val - prev);
}
public int sumRange(int left, int right) {
return tree.query(right + 1) - tree.query(left);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* NumArray obj = new NumArray(nums);
* obj.update(index,val);
* int param_2 = obj.sumRange(left,right);
*/
class BinaryIndexedTree {
public:
int n;
vector<int> c;
BinaryIndexedTree(int _n)
: n(_n)
, c(_n + 1) {}
void update(int x, int delta) {
while (x <= n) {
c[x] += delta;
x += x & -x;
}
}
int query(int x) {
int s = 0;
while (x > 0) {
s += c[x];
x -= x & -x;
}
return s;
}
};
class NumArray {
public:
BinaryIndexedTree* tree;
NumArray(vector<int>& nums) {
int n = nums.size();
tree = new BinaryIndexedTree(n);
for (int i = 0; i < n; ++i) tree->update(i + 1, nums[i]);
}
void update(int index, int val) {
int prev = sumRange(index, index);
tree->update(index + 1, val - prev);
}
int sumRange(int left, int right) {
return tree->query(right + 1) - tree->query(left);
}
};
/**
* Your NumArray object will be instantiated and called as such:
* NumArray* obj = new NumArray(nums);
* obj->update(index,val);
* int param_2 = obj->sumRange(left,right);
*/
type BinaryIndexedTree struct {
n int
c []int
}
func newBinaryIndexedTree(n int) *BinaryIndexedTree {
c := make([]int, n+1)
return &BinaryIndexedTree{n, c}
}
func (t *BinaryIndexedTree) update(x, delta int) {
for ; x <= t.n; x += x & -x {
t.c[x] += delta
}
}
func (t *BinaryIndexedTree) query(x int) (s int) {
for ; x > 0; x -= x & -x {
s += t.c[x]
}
return s
}
type NumArray struct {
tree *BinaryIndexedTree
}
func Constructor(nums []int) NumArray {
tree := newBinaryIndexedTree(len(nums))
for i, v := range nums {
tree.update(i+1, v)
}
return NumArray{tree}
}
func (t *NumArray) Update(index int, val int) {
prev := t.SumRange(index, index)
t.tree.update(index+1, val-prev)
}
func (t *NumArray) SumRange(left int, right int) int {
return t.tree.query(right+1) - t.tree.query(left)
}
/**
* Your NumArray object will be instantiated and called as such:
* obj := Constructor(nums);
* obj.Update(index,val);
* param_2 := obj.SumRange(left,right);
*/
class BinaryIndexedTree {
private n: number;
private c: number[];
constructor(n: number) {
this.n = n;
this.c = Array(n + 1).fill(0);
}
update(x: number, delta: number): void {
while (x <= this.n) {
this.c[x] += delta;
x += x & -x;
}
}
query(x: number): number {
let s = 0;
while (x > 0) {
s += this.c[x];
x -= x & -x;
}
return s;
}
}
class NumArray {
private tree: BinaryIndexedTree;
constructor(nums: number[]) {
const n = nums.length;
this.tree = new BinaryIndexedTree(n);
for (let i = 0; i < n; ++i) {
this.tree.update(i + 1, nums[i]);
}
}
update(index: number, val: number): void {
const prev = this.sumRange(index, index);
this.tree.update(index + 1, val - prev);
}
sumRange(left: number, right: number): number {
return this.tree.query(right + 1) - this.tree.query(left);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* var obj = new NumArray(nums)
* obj.update(index,val)
* var param_2 = obj.sumRange(left,right)
*/
class BinaryIndexedTree {
private int n;
private int[] c;
public BinaryIndexedTree(int n) {
this.n = n;
c = new int[n + 1];
}
public void Update(int x, int delta) {
while (x <= n) {
c[x] += delta;
x += x & -x;
}
}
public int Query(int x) {
int s = 0;
while (x > 0) {
s += c[x];
x -= x & -x;
}
return s;
}
}
public class NumArray {
private BinaryIndexedTree tree;
public NumArray(int[] nums) {
int n = nums.Length;
tree = new BinaryIndexedTree(n);
for (int i = 0; i < n; ++i) {
tree.Update(i + 1, nums[i]);
}
}
public void Update(int index, int val) {
int prev = SumRange(index, index);
tree.Update(index + 1, val - prev);
}
public int SumRange(int left, int right) {
return tree.Query(right + 1) - tree.Query(left);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* NumArray obj = new NumArray(nums);
* obj.Update(index,val);
* int param_2 = obj.SumRange(left,right);
*/
线段树将整个区间分割为多个不连续的子区间,子区间的数量不超过
- 线段树的每个节点代表一个区间;
- 线段树具有唯一的根节点,代表的区间是整个统计范围,如
$[1, N]$ ; - 线段树的每个叶子节点代表一个长度为
$1$ 的元区间$[x, x]$ ; - 对于每个内部节点
$[l, r]$ ,它的左儿子是$[l, mid]$ ,右儿子是$[mid + 1, r]$ , 其中$mid = \lfloor \frac{l + r}{2} \rfloor$ (即向下取整)。
对于本题,构造函数的时间复杂度为
class Node:
__slots__ = ["l", "r", "v"]
def __init__(self):
self.l = self.r = self.v = 0
class SegmentTree:
__slots__ = ["nums", "tr"]
def __init__(self, nums):
self.nums = nums
n = len(nums)
self.tr = [Node() for _ in range(n << 2)]
self.build(1, 1, n)
def build(self, u, l, r):
self.tr[u].l, self.tr[u].r = l, r
if l == r:
self.tr[u].v = self.nums[l - 1]
return
mid = (l + r) >> 1
self.build(u << 1, l, mid)
self.build(u << 1 | 1, mid + 1, r)
self.pushup(u)
def modify(self, u, x, v):
if self.tr[u].l == x and self.tr[u].r == x:
self.tr[u].v = v
return
mid = (self.tr[u].l + self.tr[u].r) >> 1
if x <= mid:
self.modify(u << 1, x, v)
else:
self.modify(u << 1 | 1, x, v)
self.pushup(u)
def query(self, u, l, r):
if self.tr[u].l >= l and self.tr[u].r <= r:
return self.tr[u].v
mid = (self.tr[u].l + self.tr[u].r) >> 1
result = 0
if l <= mid:
result += self.query(u << 1, l, r)
if r > mid:
result += self.query(u << 1 | 1, l, r)
return result
def pushup(self, u):
self.tr[u].v = self.tr[u << 1].v + self.tr[u << 1 | 1].v
class NumArray:
__slots__ = ["tree"]
def __init__(self, nums: List[int]):
self.tree = SegmentTree(nums)
def update(self, index: int, val: int) -> None:
self.tree.modify(1, index + 1, val)
def sumRange(self, left: int, right: int) -> int:
return self.tree.query(1, left + 1, right + 1)
# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# obj.update(index,val)
# param_2 = obj.sumRange(left,right)
class Node {
int l;
int r;
int v;
}
class SegmentTree {
private Node[] tr;
private int[] nums;
public SegmentTree(int[] nums) {
this.nums = nums;
int n = nums.length;
tr = new Node[n << 2];
for (int i = 0; i < tr.length; ++i) {
tr[i] = new Node();
}
build(1, 1, n);
}
public void build(int u, int l, int r) {
tr[u].l = l;
tr[u].r = r;
if (l == r) {
tr[u].v = nums[l - 1];
return;
}
int mid = (l + r) >> 1;
build(u << 1, l, mid);
build(u << 1 | 1, mid + 1, r);
pushup(u);
}
public void modify(int u, int x, int v) {
if (tr[u].l == x && tr[u].r == x) {
tr[u].v = v;
return;
}
int mid = (tr[u].l + tr[u].r) >> 1;
if (x <= mid) {
modify(u << 1, x, v);
} else {
modify(u << 1 | 1, x, v);
}
pushup(u);
}
public int query(int u, int l, int r) {
if (tr[u].l >= l && tr[u].r <= r) {
return tr[u].v;
}
int mid = (tr[u].l + tr[u].r) >> 1;
int v = 0;
if (l <= mid) {
v += query(u << 1, l, r);
}
if (r > mid) {
v += query(u << 1 | 1, l, r);
}
return v;
}
public void pushup(int u) {
tr[u].v = tr[u << 1].v + tr[u << 1 | 1].v;
}
}
class NumArray {
private SegmentTree tree;
public NumArray(int[] nums) {
tree = new SegmentTree(nums);
}
public void update(int index, int val) {
tree.modify(1, index + 1, val);
}
public int sumRange(int left, int right) {
return tree.query(1, left + 1, right + 1);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* NumArray obj = new NumArray(nums);
* obj.update(index,val);
* int param_2 = obj.sumRange(left,right);
*/
class Node {
public:
int l;
int r;
int v;
};
class SegmentTree {
public:
vector<Node*> tr;
vector<int> nums;
SegmentTree(vector<int>& nums) {
this->nums = nums;
int n = nums.size();
tr.resize(n << 2);
for (int i = 0; i < tr.size(); ++i) tr[i] = new Node();
build(1, 1, n);
}
void build(int u, int l, int r) {
tr[u]->l = l;
tr[u]->r = r;
if (l == r) {
tr[u]->v = nums[l - 1];
return;
}
int mid = (l + r) >> 1;
build(u << 1, l, mid);
build(u << 1 | 1, mid + 1, r);
pushup(u);
}
void modify(int u, int x, int v) {
if (tr[u]->l == x && tr[u]->r == x) {
tr[u]->v = v;
return;
}
int mid = (tr[u]->l + tr[u]->r) >> 1;
if (x <= mid)
modify(u << 1, x, v);
else
modify(u << 1 | 1, x, v);
pushup(u);
}
int query(int u, int l, int r) {
if (tr[u]->l >= l && tr[u]->r <= r) return tr[u]->v;
int mid = (tr[u]->l + tr[u]->r) >> 1;
int v = 0;
if (l <= mid) v += query(u << 1, l, r);
if (r > mid) v += query(u << 1 | 1, l, r);
return v;
}
void pushup(int u) {
tr[u]->v = tr[u << 1]->v + tr[u << 1 | 1]->v;
}
};
class NumArray {
public:
SegmentTree* tree;
NumArray(vector<int>& nums) {
tree = new SegmentTree(nums);
}
void update(int index, int val) {
return tree->modify(1, index + 1, val);
}
int sumRange(int left, int right) {
return tree->query(1, left + 1, right + 1);
}
};
/**
* Your NumArray object will be instantiated and called as such:
* NumArray* obj = new NumArray(nums);
* obj->update(index,val);
* int param_2 = obj->sumRange(left,right);
*/
type Node struct {
l, r, v int
}
type SegmentTree struct {
tr []Node
nums []int
}
func newSegmentTree(nums []int) *SegmentTree {
n := len(nums)
tr := make([]Node, n<<2)
for i := range tr {
tr[i] = Node{}
}
tree := &SegmentTree{
tr: tr,
nums: nums,
}
tree.build(1, 1, n)
return tree
}
func (tree *SegmentTree) build(u, l, r int) {
tree.tr[u].l, tree.tr[u].r = l, r
if l == r {
tree.tr[u].v = tree.nums[l-1]
return
}
mid := (l + r) >> 1
tree.build(u<<1, l, mid)
tree.build(u<<1|1, mid+1, r)
tree.pushup(u)
}
func (tree *SegmentTree) modify(u, x, v int) {
if tree.tr[u].l == x && tree.tr[u].r == x {
tree.tr[u].v = v
return
}
mid := (tree.tr[u].l + tree.tr[u].r) >> 1
if x <= mid {
tree.modify(u<<1, x, v)
} else {
tree.modify(u<<1|1, x, v)
}
tree.pushup(u)
}
func (tree *SegmentTree) query(u, l, r int) (v int) {
if tree.tr[u].l >= l && tree.tr[u].r <= r {
return tree.tr[u].v
}
mid := (tree.tr[u].l + tree.tr[u].r) >> 1
if l <= mid {
v += tree.query(u<<1, l, r)
}
if r > mid {
v += tree.query(u<<1|1, l, r)
}
return v
}
func (tree *SegmentTree) pushup(u int) {
tree.tr[u].v = tree.tr[u<<1].v + tree.tr[u<<1|1].v
}
type NumArray struct {
tree *SegmentTree
}
func Constructor(nums []int) NumArray {
return NumArray{
tree: newSegmentTree(nums),
}
}
func (this *NumArray) Update(index int, val int) {
this.tree.modify(1, index+1, val)
}
func (this *NumArray) SumRange(left int, right int) int {
return this.tree.query(1, left+1, right+1)
}
/**
* Your NumArray object will be instantiated and called as such:
* obj := Constructor(nums);
* obj.Update(index,val);
* param_2 := obj.SumRange(left,right);
*/
class Node {
l: number;
r: number;
v: number;
}
class SegmentTree {
private tr: Node[];
private nums: number[];
constructor(nums: number[]) {
this.nums = nums;
const n = nums.length;
this.tr = new Array<Node>(n << 2);
for (let i = 0; i < this.tr.length; ++i) {
this.tr[i] = { l: 0, r: 0, v: 0 };
}
this.build(1, 1, n);
}
build(u: number, l: number, r: number): void {
this.tr[u].l = l;
this.tr[u].r = r;
if (l == r) {
this.tr[u].v = this.nums[l - 1];
return;
}
const mid = (l + r) >> 1;
this.build(u << 1, l, mid);
this.build((u << 1) | 1, mid + 1, r);
this.pushup(u);
}
modify(u: number, x: number, v: number): void {
if (this.tr[u].l == x && this.tr[u].r == x) {
this.tr[u].v = v;
return;
}
const mid = (this.tr[u].l + this.tr[u].r) >> 1;
if (x <= mid) {
this.modify(u << 1, x, v);
} else {
this.modify((u << 1) | 1, x, v);
}
this.pushup(u);
}
query(u: number, l: number, r: number): number {
if (this.tr[u].l >= l && this.tr[u].r <= r) {
return this.tr[u].v;
}
const mid = (this.tr[u].l + this.tr[u].r) >> 1;
let v = 0;
if (l <= mid) {
v += this.query(u << 1, l, r);
}
if (r > mid) {
v += this.query((u << 1) | 1, l, r);
}
return v;
}
pushup(u: number): void {
this.tr[u].v = this.tr[u << 1].v + this.tr[(u << 1) | 1].v;
}
}
class NumArray {
private tree: SegmentTree;
constructor(nums: number[]) {
this.tree = new SegmentTree(nums);
}
update(index: number, val: number): void {
this.tree.modify(1, index + 1, val);
}
sumRange(left: number, right: number): number {
return this.tree.query(1, left + 1, right + 1);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* var obj = new NumArray(nums)
* obj.update(index,val)
* var param_2 = obj.sumRange(left,right)
*/
public class Node {
public int l;
public int r;
public int v;
}
public class SegmentTree {
private Node[] tr;
private int[] nums;
public SegmentTree(int[] nums) {
this.nums = nums;
int n = nums.Length;
tr = new Node[n << 2];
for (int i = 0; i < tr.Length; ++i) {
tr[i] = new Node();
}
Build(1, 1, n);
}
public void Build(int u, int l, int r) {
tr[u].l = l;
tr[u].r = r;
if (l == r) {
tr[u].v = nums[l - 1];
return;
}
int mid = (l + r) >> 1;
Build(u << 1, l, mid);
Build(u << 1 | 1, mid + 1, r);
Pushup(u);
}
public void Modify(int u, int x, int v) {
if (tr[u].l == x && tr[u].r == x) {
tr[u].v = v;
return;
}
int mid = (tr[u].l + tr[u].r) >> 1;
if (x <= mid) {
Modify(u << 1, x, v);
} else {
Modify(u << 1 | 1, x, v);
}
Pushup(u);
}
public int Query(int u, int l, int r) {
if (tr[u].l >= l && tr[u].r <= r) {
return tr[u].v;
}
int mid = (tr[u].l + tr[u].r) >> 1;
int v = 0;
if (l <= mid) {
v += Query(u << 1, l, r);
}
if (r > mid) {
v += Query(u << 1 | 1, l, r);
}
return v;
}
public void Pushup(int u) {
tr[u].v = tr[u << 1].v + tr[u << 1 | 1].v;
}
}
public class NumArray {
private SegmentTree tree;
public NumArray(int[] nums) {
tree = new SegmentTree(nums);
}
public void Update(int index, int val) {
tree.Modify(1, index + 1, val);
}
public int SumRange(int left, int right) {
return tree.Query(1, left + 1, right + 1);
}
}
/**
* Your NumArray object will be instantiated and called as such:
* NumArray obj = new NumArray(nums);
* obj.Update(index,val);
* int param_2 = obj.SumRange(left,right);
*/