HDU 1698 Just a Hook

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1.题目描述：点击打开链接

2.解题思路：本题是线段树的区间更新的基础题，要求把给定的区间中的数都设置为v，然后求和。解法不予赘述。不过注意初始化时候lazy标记均为1。

3.代码：

#include<iostream>#include<algorithm>#include<cassert>#include<string>#include<sstream>#include<set>#include<bitset>#include<vector>#include<stack>#include<map>#include<queue>#include<deque>#include<cstdlib>#include<cstdio>#include<cstring>#include<cmath>#include<ctime>#include<cctype>#include<list>#include<complex>#include<functional>#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;#define me(s)  memset(s,0,sizeof(s))#define rep(i,n) for(int i=0;i<(n);i++)typedef long long ll;typedef unsigned int uint;typedef unsigned long long ull;typedef pair <ll, ll> P;#define lid (id<<1)#define rid (id<<1|1)const int N=100000+10;struct Node{    int l,r;    int lazy;    int val;    int mid(){return l+(r-l)/2;}    void fun(int x)    {        lazy=x;        val=(r-l+1)*x;    }}tr[N*4];void pushup(int id){    tr[id].val=tr[lid].val+tr[rid].val;}void build(int id,int L,int R){    tr[id].l=L,tr[id].r=R;    tr[id].lazy=1;    if(L==R){tr[id].val=1;return;}    int mid=tr[id].mid();    build(lid,L,mid);    build(rid,mid+1,R);    pushup(id);}void pushdown(int id){    if(tr[id].lazy)    {        tr[lid].fun(tr[id].lazy);        tr[rid].fun(tr[id].lazy);        tr[id].lazy=0;    }}void update(int id,int L,int R,int val){    int l=tr[id].l,r=tr[id].r;    if(L<=l&&r<=R){tr[id].fun(val);return;}    int mid=tr[id].mid();    pushdown(id);    if(L<=mid)update(lid,L,R,val);    if(R>mid)update(rid,L,R,val);    pushup(id);}int main(){    int T;    int rnd=0;    scanf("%d",&T);    while(T--)    {        int n,q;        scanf("%d%d",&n,&q);        build(1,1,n);        int l,r,x;        while(q--)        {            scanf("%d%d%d",&l,&r,&x);            update(1,l,r,x);        }        printf("Case %d: The total value of the hook is %d.\n",++rnd,tr[1].val);    }}

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