HDU 1698 Just a Hook 线段树+lazy-target 区间刷新

Just a Hook

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 30553    Accepted Submission(s): 15071

Problem Description

In the game of DotA, Pudge’s meat hook is actually the most horrible thing for most of the heroes. The hook is made up of several 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 each operation, Pudge can change the consecutive metallic sticks, numbered from X to Y, into cupreous sticks, silver sticks or golden sticks.
The total value of the hook is calculated as the sum of values of N metallic sticks. More precisely, the value for each kind of stick is calculated as follows:

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 the operations.
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 than 10 cases.
For each case, the first line contains an integer N, 1<=N<=100,000, which is the number of the sticks of Pudge’s meat hook and the second line contains an 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 to Y into the metal kind Z, where Z=1 represents the cupreous kind, Z=2 represents the silver kind and Z=3 represents the golden kind.

 

Output

For each case, print a number in a line representing the total value of the hook after the operations. Use the format in 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.

 

题意：

就是说刚开始所有的棍子都是铜色，然后去成段的刷，铜色的赋值为1，银色的赋值为2，金色的赋值为3。当然，后来刷上的颜色会覆盖掉原来的颜色，最后输出整个区间的和。

思路：

线段树+lazy-target标记（pushdown函数，将自身的lazy标记传递给儿子结点，并计算儿子几点成段跟新的值）

代码：

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<string>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int maxn=100005;
int color[maxn<<2],sum[maxn<<2];
void pushup(int rt) {
    sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}
void pushdown(int rt, int m) {
    if(color[rt]) {
        color[rt<<1]=color[rt<<1|1]=color[rt];
        sum[rt<<1]=(m-(m>>1))*color[rt];//左儿子区间跟新数值
        sum[rt<<1|1]=(m>>1)*color[rt];//右儿子区间跟新数值
        color[rt]=0;
    }
}
void build(int l, int r, int rt) {
    sum[rt]=1;color[rt]=0;
    if(l==r) return;
    int mid=(l+r)>>1;
    build(lson);
    build(rson);
    pushup(rt);
}
void update(int L, int R, int c, int l, int r, int rt) {
    if(L<=l&&r<=R) {
        color[rt]=c;
        sum[rt]=c*(r-l+1);
        return;
    }
    pushdown(rt,r-l+1);//传递标记
    int mid=(l+r)>>1;
    if(L<=mid) update(L,R,c,lson);
    if(R>mid) update(L,R,c,rson);
    pushup(rt);
}
int main() {
    int t,cnt=1;
    scanf("%d",&t);
    while(t--) {
        int n,up;
        scanf("%d",&n);
        build(1,n,1);
        scanf("%d",&up);
        int L,R,c;
        for(int i=1;i<=up;i++) {
            scanf("%d%d%d",&L,&R,&c);
            update(L,R,c,1,n,1);
        }
        printf("Case %d: The total value of the hook is %d.\n",cnt++,sum[1]);
    }
    return 0;
}