hdu 1698 Just a Hook（线段树之 成段更新）

Just a Hook

                                                                            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 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：有一个N段金属组成的钩子，開始时这N段所有是cupreous，接下来有Q次操作，每次操作为x,y,z，表示把x到y这一段换成z。z为1时为cupreous，价值为1；z为2时为silver，价值为2。z为3时为golden。价值为3；问这个钩子最后的总价值是多少。

分析：线段树成段更新，每次记录区间和。最后输出根节点的sum就可以。

#include<cstdio>

#define lson l, mid, root<<1
#define rson mid+1, r, root<<1|1
const int N = 100010;
struct node
{
    int l;
    int r;
    int sum;
    int color;
}a[N<<2];

void PushUp(int root)
{
    a[root].sum = a[root<<1].sum + a[root<<1|1].sum;
}
void PushDown(int len, int root)
{
    if(a[root].color)
    {
        a[root<<1].color = a[root<<1|1].color = a[root].color;
        a[root<<1].sum = (len - (len>>1)) * a[root].color;
        a[root<<1|1].sum = (len>>1) * a[root].color;
        a[root].color = 0;
    }
}
void build_tree(int l, int r, int root)
{
    a[root].l = l;
    a[root].r = r;
    a[root].color = 0;

    if(l == r)
    {
        a[root].sum = 1;
        return ;
    }
    int mid = (l + r) >> 1;
    build_tree(lson);
    build_tree(rson);
    PushUp(root);
}
void update(int l, int r, int root, int z)
{
    if(l <= a[root].l && r >= a[root].r)
    {
        a[root].color = z;
        a[root].sum = (a[root].r - a[root].l + 1) * z;
        return;
    }
    PushDown(a[root].r - a[root].l + 1, root);
    int mid = (a[root].l + a[root].r) >> 1;
    if(l <= mid) update(l, r, root<<1, z);
    if(r > mid) update(l, r, root<<1|1, z);
    PushUp(root);
}

int main()
{
    int T, n, m, cas = 0;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        build_tree(1, n, 1);
        scanf("%d",&m);
        int x, y, z;
        while(m--)
        {
            scanf("%d%d%d",&x,&y,&z);
            update(x, y, 1, z);
        }
        int ans = a[1].sum;
        printf("Case %d: The total value of the hook is %d.
", ++cas, ans);
    }
    return 0;
}