POJ3468 A Simple Problem with Integers

解题思路：线段树区间更新模板题，注意比较与点更新的区别。不解释，上代码：

#include<cstdio>
using namespace std;
#define lson l, m, rt << 1
#define rson m+1, r, rt << 1 | 1
#define LL long long
#define maxn 100005
LL sum[maxn<<2], add[maxn<<2];

void PushUp(int rt)
{
    sum[rt] = sum[rt<<1] + sum[rt<<1 | 1];
}

void PushDown(int rt, int m)
{
    if(add[rt])
    {
        add[rt<<1] += add[rt];
        add[rt<<1|1] += add[rt];
        sum[rt<<1] += (m - (m>>1)) * add[rt];
        sum[rt<<1|1] += (m >> 1) * add[rt];
        add[rt] = 0;
    }
    return ;
}

void Build(int l, int r, int rt)
{
    add[rt] = 0;
    if(l == r)
    {
        scanf("%I64d", &sum[rt]);
        return ;
    }
    int m = (l + r) >> 1;
    Build(lson);
    Build(rson);
    PushUp(rt);
}

LL Query(int L, int R, int l, int r, int rt)
{
    if(L <= l && R >= r) return sum[rt];
    PushDown(rt, r-l+1);
    int m = (l + r) >> 1;
    LL ret = 0;
    if(L <= m) ret += Query(L, R, lson);
    if(R > m) ret += Query(L, R, rson);
    return ret;
}

void Update(int L, int R, int c, int l, int r, int rt)
{
    if(L <= l && R >= r)
    {
        add[rt] += c;
        sum[rt] += (LL)c * (r - l + 1);
        return ;
    }
    PushDown(rt, r - l + 1);
    int m = (l + r) >> 1;
    if(L <= m) Update(L, R, c, lson);
    if(R > m) Update(L, R, c, rson);
    PushUp(rt);
}

int main()
{
    int n, m, a, b, c;
    char str[5];
    scanf("%d %d", &n, &m);
    Build(1, n, 1);
    while(m--)
    {
        scanf("%s", str);
        if(str[0] == 'Q')
        {
            scanf("%d %d", &a, &b);
            LL ans = Query(a, b, 1, n, 1);
            printf("%I64d
", ans);
        }
        else
        {
            scanf("%d %d %d", &a, &b, &c);
            Update(a, b, c, 1, n, 1);
        }
    }
    return 0;
}