POJ 3468 A Simple Problem with Integers （区间增减）

线段树的区间增减，水题，帮助练手

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>

#define max(a,b) (a>b)?a:b
#define min(a,b) (a>b)?b:a
#define lson l , m , rt << 1
#define rson m + 1 , r , rt << 1 | 1
#define LL __int64
const int maxn = 500100;
using namespace std;
#define MAX INT_MAX
#define MIN INT_MIN
struct node
{
int l,r;
LL add,sum; //add作为一个数的累加和，同时起标记的作用；
}T[300010];
int a[100005]; //add必须是__int64；
void putup(int id)
{
T[id].sum=T[2*id].sum+T[2*id+1].sum;
}
void putdown(int id)
{
if(T[id].add)
{
T[2*id].add+=T[id].add;
T[2*id].sum += (T[2*id].r-T[2*id].l+1)*T[id].add;
T[2*id+1].add+=T[id].add;
T[2*id+1].sum += (T[2*id+1].r-T[2*id+1].l+1)*T[id].add;
T[id].add=0;
}
}
void creat(int l,int r,int id)
{
T[id].l=l;
T[id].r=r;
T[id].add=0;
if(l==r)
{
T[id].sum=a[r];
return;
}
int mid=(l+r)>>1;
creat(l,mid,2*id);
creat(mid+1,r,2*id+1);
putup(id);
}
void update(int from,int to,LL add,int id)
{
if(from<=T[id].l&&to>=T[id].r)
{
T[id].add +=add;
T[id].sum += (T[id].r-T[id].l+1)*add;
return;
}

putdown(id);
if(from<=T[2*id].r)
update(from,to,add,2*id);
if(to>=T[2*id+1].l)
update(from,to,add,2*id+1);
putup(id);
}
LL query(int from,int to,int id)
{
if(from==T[id].l&&to==T[id].r)
return T[id].sum;

putdown(id);
if(from>=T[2*id+1].l)
return query(from,to,2*id+1);
else if(to<=T[2*id].r)
return query(from,to,2*id);
else
return query(from,T[2*id].r,2*id) + query(T[2*id+1].l,to,2*id+1);
}
int main()
{
int n,m,A,B;
LL add;
char str[5];
while(scanf("%d%d",&n,&m)!=EOF)
{
for(int i=1; i<=n; i++)
scanf("%d",&a[i]);
creat(1,n,1);
while(m--)
{
LL ans = 0;
scanf("%s",str);
if(str[0]=='C')
{
scanf("%d%d%I64d",&A,&B,&add);
update(A,B,add,1);
}
else
{
scanf("%d%d",&A,&B);
ans=query(A,B,1);
printf("%I64d\n",ans);
}
}
}
}