PKU 3468

题目链接：

http://poj.org/problem?id=3468

题解 ：

线段树区间更新模版题。

代码：

#include <string>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define met(a,b) memset(a,b,sizeof(a))
#define inf 0x3f3f3f3f
#define lchild rt<<1 ,l, m
#define rchild rt<<1|1 ,m+1, r
typedef long long ll;
const ll maxn = 1e5+10;
ll tree[maxn<<2];
ll lazy[maxn<<2];

void push_up(ll rt)
{
    tree[rt]=tree[rt << 1]+tree[rt<<1|1];
}

void push_down(ll rt, ll len)
{
    tree[rt << 1] += lazy[rt] * (len - (len >> 1));
    lazy[rt << 1] += lazy[rt];
    tree[rt << 1 | 1] += lazy[rt] * (len >> 1);
    lazy[rt << 1 | 1] += lazy[rt];
    lazy[rt] = 0;
}

void build(ll rt,ll l,ll r)
{
    lazy[rt]=0;
    if(l==r)
    {
        scanf("%lld",&tree[rt]);
        return;
    }
    ll m=(l+r)>>1;
    build(lchild);
    build(rchild);
    push_up(rt);
}

void update(ll L, ll R, ll delta, ll rt, ll l, ll r )
{
    if (L <= l && r <= R) {
        tree[rt] += delta * (r - l + 1);
        lazy[rt] += delta;
        return;
    }
    if (lazy[rt]) push_down(rt, r - l + 1);
    ll m = (l + r) >> 1;
    if (L <= m) update(L, R, delta, lchild);
    if (R > m)  update(L, R, delta, rchild);
    push_up(rt);
}

ll query(ll L, ll R, ll rt, ll l, ll r)
{
    if (L <= l && r <= R) return tree[rt];
    if (lazy[rt]) push_down(rt, r - l + 1);
    ll m = (l + r) >> 1, ret = 0;
    if (L <= m) ret += query(L, R, lchild);
    if (R > m)  ret += query(L, R, rchild);
    return ret;
}

int main()
{
    ll n,q;
    while(scanf("%lld%lld",&n,&q)!=EOF)
    {
        build(1,1,n);
        while(q--)
        {
            char s[10];
            scanf("%s",s);
            if(s[0]=='C')
            {
                ll a,b,c;
                scanf("%lld%lld%lld",&a,&b,&c);
                update(a,b,c,1,1,n);
            }
            if(s[0]=='Q')
            {
                ll a,b;
                scanf("%lld%lld",&a,&b);
                printf("%lld\n",query(a,b,1,1,n));
            }
        }
    }
}