A Simple Problem with Integers POJ 3468

题目链接：   http://poj.org/problem?id=3468

题意： 给出一个序列，然后会有两种操作，一是让下标从 i - j 都增加 某个固定值， 二是询问你下标从 m - n 这个区域的和是多少？

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <map>
#include <stack>
#include <cstring>
using namespace std;
typedef long long LL;
#define INF 0xfffffff
#define maxn 110000
#define lson rt<<1
#define rson rt<<1|1
int A[maxn];

struct node
{
  int l, r;
  int len()
  {
      return r-l+1;
  }
  LL s, e;
} tree[maxn<<2];

void build(int l, int r, int rt)
{
    tree[rt].l = l;
    tree[rt].r = r;
    tree[rt].e = 0;

    if(l == r)
    {
        tree[rt].s = A[l];
        return ;
    }

    int mid = (l+r)/2;

    build(l, mid, lson);
    build(mid+1, r, rson);

    tree[rt].s = tree[lson].s + tree[rson].s;
}

void down(int rt)
{
    tree[lson].s += tree[lson].len()*tree[rt].e;
    tree[rson].s += tree[rson].len()*tree[rt].e;

    tree[lson].e += tree[rt].e;
    tree[rson].e += tree[rt].e;

    tree[rt].e = 0;
}

void update(int l, int r, int val, int rt)
{
        tree[rt].s += val*(r-l+1);

   if(tree[rt].l == l && tree[rt].r == r)
   {
       tree[rt].e += val;
       return ;
   }

      down(rt);

    int mid = (tree[rt].l + tree[rt].r)/2;

    if(r<=mid) update(l, r, val, lson);
    else if(l>mid) update(l, r, val, rson);
    else
        {
          update(l, mid, val, lson);
          update(mid+1, r, val, rson);
        }
}

LL query(int l, int r, int rt)
{

    if(tree[rt].l == l && r == tree[rt].r)
        return tree[rt].s;

        down(rt);

     int mid = (tree[rt].l + tree[rt].r)/2;
     if(r<=mid) return query(l, r, lson);
     else if(l>mid) return query(l, r, rson);
     else
     {
        LL  lsum, rsum;
        lsum = query(l, mid, lson);
        rsum = query(mid+1, r, rson);
        return lsum+rsum;
     }
}

int main()
{
    int n, m, a, b, c;
    char op;

    scanf("%d %d",&n, &m);

        for(int i=1; i<=n; i++)
            scanf("%d", &A[i]);

            build(1, n, 1);

        while(m --)
        {
            getchar();

            scanf("%c %d %d", &op, &a, &b);
            
            if(op=='Q')
               {
                  LL ans = query(a, b, 1);
                  printf("%I64d
", ans);

                    continue;
               }
               scanf("%d", &c);
            update(a, b, c, 1);
        }

    return 0;
}