A Simple Problem with Integers---poj3468线段树

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

#define INF 0xfffffff
#define N 100050
#define Lson root<<1
#define Rson root<<1|1

struct SegmentTree
{
    int L, R;
    long long sum, k;
    int Mid()
    {
        return (L+R)>>1;
    }
    int len()
    {
        return R-L+1;
    }
}a[N<<2];

void BuildSegTree(int root, int L, int R)
{
    a[root].L = L; a[root].R = R; a[root].k = 0;
    if( L == R )
    {
        scanf("%lld", &a[root].sum);
        return ;
    }

    BuildSegTree(Lson, L, a[root].Mid());
    BuildSegTree(Rson, a[root].Mid()+1, R);

    a[root].sum = a[Rson].sum + a[Lson].sum;
}
void PushDown(int root)
{
    a[Lson].sum += a[root].k * a[Lson].len();
    a[Lson].k += a[root].k;
    a[Rson].sum += a[root].k * a[Rson].len();
    a[Rson].k += a[root].k;

    a[root].k = 0;
}
void Update(int root, int L, int R, int k)
{
    a[root].sum += (R - L + 1) * k;
    if(a[root].L == L && a[root].R == R)
    {
        a[root].k += k;
        return ;
    }

    PushDown(root);

    if(R <= a[root].Mid())
        Update(Lson, L, R, k);
    else if(L > a[root].Mid())
        Update(Rson, L, R, k);
    else
    {
        Update(Lson, L, a[root].Mid(), k);
        Update(Rson, a[root].Mid()+1, R, k);
    }
}
long long Query(int root, int L, int R)
{
    if(a[root].L==L && a[root].R == R)
        return a[root].sum;

    PushDown(root);

    if(R <= a[root].Mid())
        return Query(Lson, L, R);
    else if( L > a[root].Mid())
        return Query(Rson, L, R);
    else
    {
        long long Lsum = Query(Lson, L, a[root].Mid());
        long long Rsum = Query(Rson, a[root].Mid()+1, R);
        return Lsum + Rsum;
    }
}

int main()
{
    int n, m, L, R, k;
    long long ans;
    char s[10];
    while(scanf("%d %d", &n, &m) != EOF)
    {
        BuildSegTree(1, 1, n);
        for(int i=0; i<m; i++)
        {
            scanf("%s", s);
            if(s[0] == ‘Q‘)
            {
                scanf("%d %d", &L, &R);
                ans = Query(1, L, R);
                printf("%lld\n", ans);
            }
            else
            {
                scanf("%d %d %d", &L, &R, &k);
                Update(1, L, R, k);
            }
        }
    }
    return 0;
}