HDU1698 Just a Hook
标签：线段树
http://www.sakurasake.icoc.me/nd.jsp?id=6#_np=2_327
Time Limit: 4000/2000 MS(Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Problem Description
In the game of DotA, Pudge’s meat hook isactually the most horrible thing for most of the heroes. The hook is made up ofseveral consecutive metallic sticks which are of the same length.
Now Pudge wants to do some operations on the hook.
Let us number the consecutive metallic sticks of the hook from 1 to N. For eachoperation, Pudge can change the consecutive metallic sticks, numbered from X toY, into cupreous sticks, silver sticks or golden sticks.
The total value of the hook is calculated as the sum of values of N metallicsticks. More precisely, the value for each kind of stick is calculated asfollows:
For each cupreous stick, the value is 1.
For each silver stick, the value is 2.
For each golden stick, the value is 3.
Pudge wants to know the total value of the hook after performing theoperations.
You may consider the original hook is made up of cupreous sticks.
Input
The input consists of several test cases.The first line of the input is the number of the cases. There are no more than10 cases.
For each case, the first line contains an integer N, 1<=N<=100,000, whichis the number of the sticks of Pudge’s meat hook and the second line containsan integer Q, 0<=Q<=100,000, which is the number of the operations.
Next Q lines, each line contains three integers X, Y, 1<=X<=Y<=N, Z,1<=Z<=3, which defines an operation: change the sticks numbered from X toY into the metal kind Z, where Z=1 represents the cupreous kind, Z=2 representsthe silver kind and Z=3 represents the golden kind.
Output
For each case, print a number in a linerepresenting the total value of the hook after the operations. Use the formatin the example.
Sample Input
1
10
2
1 5 2
5 9 3
Sample Output
Case 1: The total value of the hook is 24.
Source
2008“Sunline Cup” National Invitational Contest
分析：这题与前几道线段树入门题不同的是，成段更新，总区间求和。
用st数组标记，0代表改点为杂色，1,2,3为纯色，更新时，如果某段节点为纯色，那么其左右儿子也为纯色
#include<iostream>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<ctime>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<queue>
#include<stack>
#define lson l,m,k<<1
#define rson m+1,r,k<<1|1
#define N 100001
inline int read()
{
int f=1,x=0;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
using namespace std;
int st[N<<2];
int flag;
void make(int l,int r,int k)
{
st[k]=flag;
if(l==r)return;
int m=(l+r)>>1;
make(lson);
make(rson);
}
void down(int &k)
{
st[k<<1]=st[k<<1|1]=st[k];
st[k]=0;
}
void change(int &L,int &R,int l,int r,int k)
{
if(L<=l&&R>=r)
{
st[k]=flag;
return;
}//如果寻找需要更新的线段正好处于某个区间内，那么一整段都更新
if(st[k])down(k);//如果该节点为纯色，那么down操作，左右儿子颜色更新为纯色
int m=(l+r)>>1;
if(L<=m)change(L,R,lson);
if(R>m)change(L,R,rson);//分别递归更新左右儿子
}
int query(int l,int r,int k)
{
if(st[k])
return st[k]*(r-l+1);
int m=(l+r)>>1,t1,t2;
t1=query(lson);
t2=query(rson);
return t1+t2;
}
int main()
{
int T,n,t=1;
int L,R,q;
T=read();
while(T--)
{
n=read();q=read();
flag=1;
make(1,n,1);
while(q--)
{
L=read();R=read();flag=read();
change(L,R,1,n,1);//更新L-R,从1-n,st[1]开始
}
printf("Case %d: The total value of the hook is %d.\n",t++,query(1,n,1));
}
return 0;
}
