对于小Ho表现出的对线段树的理解,小Hi表示挺满意的,但是满意就够了么?于是小Hi将问题改了改,又出给了小Ho:
假设货架上从左到右摆放了N种商品,并且依次标号为1到N,其中标号为i的商品的价格为Pi。小Hi的每次操作分为两种可能,第一种是修改价格——小Hi给出一段区间[L, R]和一个新的价格NewP,所有标号在这段区间中的商品的价格都变成NewP。第二种操作是询问——小Hi给出一段区间[L, R],而小Ho要做的便是计算出所有标号在这段区间中的商品的总价格,然后告诉小Hi。
那么这样的一个问题,小Ho该如何解决呢?
提示:推动科学发展的除了人的好奇心之外还有人的懒惰心!
每个测试点(输入文件)有且仅有一组测试数据。
每组测试数据的第1行为一个整数N,意义如前文所述。
每组测试数据的第2行为N个整数,分别描述每种商品的重量,其中第i个整数表示标号为i的商品的重量Pi。
每组测试数据的第3行为一个整数Q,表示小Hi进行的操作数。
每组测试数据的第N+4~N+Q+3行,每行分别描述一次操作,每行的开头均为一个属于0或1的数字,分别表示该行描述一个询问和一次商品的价格的更改两种情况。对于第N+i+3行,如果该行描述一个询问,则接下来为两个整数Li, Ri,表示小Hi询问的一个区间[Li, Ri];如果该行描述一次商品的价格的更改,则接下来为三个整数Li,Ri,NewP,表示标号在区间[Li, Ri]的商品的价格全部修改为NewP。
对于100%的数据,满足N<=10^5,Q<=10^5, 1<=Li<=Ri<=N,1<=Pi<=N, 0 对于每组测试数据,对于每个小Hi的询问,按照在输入中出现的顺序,各输出一行,表示查询的结果:标号在区间[Li, Ri]中的所有商品的价格之和。 输出
10 4733 6570 8363 7391 4511 1433 2281 187 5166 378 6 1 5 10 1577 1 1 7 3649 0 8 10 0 1 4 1 6 8 157 1 3 4 1557样例输出
4731 14596
参考:hihoCoder线段树的区间修改
using System;
namespace SegmentTree
{
class Program
{
static void Main()
{
int N = int.Parse(Console.ReadLine());
string[] inputs = Console.ReadLine().Split(' ');
int[] weights = new int[N];
for (int i = 0; i < N; i++)
weights[i] = int.Parse(inputs[i]);
SegTree st = new SegTree(weights);
N = int.Parse(Console.ReadLine());
while (N-- > 0)
{
inputs = Console.ReadLine().Split(' ');
if (inputs[0] == "0")
Console.WriteLine(st.Query(int.Parse(inputs[1]), int.Parse(inputs[2])));
else
st.Modify(int.Parse(inputs[1]), int.Parse(inputs[2]), int.Parse(inputs[3]));
}
}
}
public class SegTree
{
public class TreeNode
{
public TreeNode(int start, int end, int sum = 0, bool lazy = false, TreeNode left = null, TreeNode right = null, TreeNode parent = null)
{
this.start = start;
this.end = end;
this.sum = sum;
this.lazy = lazy;
this.left = left;
this.right = right;
this.parent = parent;
}
private int start;
private int end;
private long sum;
private bool lazy;
private TreeNode left;
private TreeNode right;
private TreeNode parent;
public int StartIndex { get { return start; } }
public int EndIndex { get { return end; } }
public long Sum { get { return sum; } set { sum = value; } }
public bool Lazy { get { return lazy; } set { lazy = value; } }
public TreeNode Left { get { return left; } set { left = value; } }
public TreeNode Right { get { return right; } set { right = value; } }
public TreeNode Parent { get { return parent; } set { parent = value; } }
public long Reset()
{
if (left != null)
this.sum += left.Reset();
if (right != null)
this.sum += right.Reset();
return this.sum;
}
}
public SegTree(int[] weights) : this(1, weights.Length, weights) { }
private SegTree(int start, int end, int[] weights)
{
root = buildTree(start, end, weights);
root.Reset();
}
private TreeNode buildTree(int start, int end, int[] weights)
{
TreeNode parent = new TreeNode(start, end);
if (start == end)
parent.Sum = weights[start - 1];
else if (start < end)
{
int mid = (start + end) / 2;
parent.Left = buildTree(start, mid, weights);
parent.Left.Parent = parent;
parent.Right = buildTree(mid + 1, end, weights);
parent.Right.Parent = parent;
}
return parent;
}
private TreeNode root;
public TreeNode Root { get { return root; } }
public long Query(int left, int right)
{
return query(root, left, right);
}
private long query(TreeNode node, int left, int right)
{
if (node.StartIndex == left && node.EndIndex == right)
return node.Sum;
lazyCal(node);
int mid = (node.StartIndex + node.EndIndex) / 2;
if (mid >= right)
return query(node.Left, left, right);
else if (mid < left)
return query(node.Right, left, right);
else
{
long result = query(node.Left, left, mid);
result += query(node.Right, mid + 1, right);
return result;
}
}
private void lazyCal(TreeNode node)
{
if (node.Lazy)
{
node.Lazy = false;
if (node.StartIndex == node.EndIndex) return;
long ave = node.Sum / (node.EndIndex - node.StartIndex + 1);
if (node.Left != null)
{
node.Left.Lazy = true;
node.Left.Sum = ave * (node.Left.EndIndex - node.Left.StartIndex + 1);
}
if (node.Right != null)
{
node.Right.Lazy = true;
node.Right.Sum = ave * (node.Right.EndIndex - node.Right.StartIndex + 1);
}
}
}
public void Modify(int left, int right, int weight)
{
modify(root, left, right, weight);
}
private void modify(TreeNode node, int left, int right, int weight)
{
if (node.StartIndex == left && node.EndIndex == right)
{
node.Sum = weight * (right - left + 1);
node.Lazy = true;
TreeNode temp = node;
while (temp.Parent != null)
{
temp.Parent.Sum = temp.Parent.Left.Sum + temp.Parent.Right.Sum;
temp = temp.Parent;
}
return;
}
lazyCal(node);
int mid = (node.StartIndex + node.EndIndex) / 2;
if (mid < left)
modify(node.Right, left, right, weight);
else if (mid >= right)
modify(node.Left, left, right, weight);
else
{
modify(node.Left, left, mid, weight);
modify(node.Right, mid + 1, right, weight);
}
}
}
}