hdu5475(线段树单点修改，统计区间乘积)

题目意思：

给定a*b*c*d*e*f*....,可以在某一步去掉前面的一个因子，每次回答乘积。

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cmath>
#define LL long long
using namespace std;
LL Q,MOD;
//线段树
//区间每点增值，求区间和
const int maxN = 110000;
struct node
{
    int lt, rt;
    LL val;
}tree[4*maxN];

//向上更新
void pushUp(int id)
{
    tree[id].val = (tree[id<<1].val * tree[id<<1|1].val)%MOD;
}

//建立线段树
void build(int lt, int rt, int id)
{
    tree[id].lt = lt;
    tree[id].rt = rt;
    tree[id].val = 1;//每段的初值，根据题目要求
    if (lt == rt)
    {
        tree[id].val=1;
        return;
    }
    int mid = (lt+rt)>>1;
    build(lt, mid, id<<1);
    build(mid+1, rt, id<<1|1);
    pushUp(id);
}

//增加区间内每个点固定的值
void add(int lt, int rt, int id, int pls)
{
    if (lt <= tree[id].lt && rt >= tree[id].rt)
    {
        if(pls!=-1)
        {
          tree[id].val *= pls;
          tree[id].val %= MOD;
        }
        if(pls==-1)
          tree[id].val =1;
        return;
    }
    int mid = (tree[id].lt+tree[id].rt)>>1;
    if (lt <= mid)
        add(lt, rt, id<<1, pls);
    if (rt > mid)
        add(lt, rt, id<<1|1, pls);
    pushUp(id);
}

//查询某段区间内的和
LL query(int lt, int rt, int id)
{
    if (lt <= tree[id].lt && rt >= tree[id].rt)
        return tree[id].val;
    int mid = (tree[id].lt+tree[id].rt)>>1;
    LL ans = 1;
    if (lt <= mid)
        ans = (ans * query(lt, rt, id<<1) ) %MOD;
    if (rt > mid)
        ans = (ans * query(lt, rt, id<<1|1) ) %MOD;
    return ans;
}

int main()
{
    //freopen("test.txt","r",stdin);
    int t;
    scanf("%d",&t);
    int Case=0;
    while(t--)
    {
        scanf("%I64d%I64d",&Q,&MOD);
        build(1,Q,1);
        printf("Case #%d:\n",++Case);
        for(int i=1;i<=Q;i++)
        {
            LL x,m;
            scanf("%I64d%I64d",&x,&m);
            if(x==1)
              add(i,i,1,m);
            else if(x==2)
              add(m,m,1,-1);
            printf("%I64d\n",tree[1].val);
        }
    }
    return 0;
}