POJ 3468-A Simple Problem with Integers（線段樹+懶標記）

#include <cstdio>
using namespace std;

const int maxn=1e6+7;
typedef long long ll;

ll sumTree[maxn<<2],len[maxn<<2],lazy[maxn<<2]; //懶標記

void PushDown(int pcur) {
	if (lazy[pcur]==0)return;

    lazy[pcur<<1]+=lazy[pcur];
    lazy[pcur<<1|1]+=lazy[pcur];

    sumTree[pcur<<1]+=lazy[pcur]*len[pcur<<1];
    sumTree[pcur<<1|1]+=lazy[pcur]*len[pcur<<1|1];

    lazy[pcur]=0;
}

void Build(int pl,int pr,int pcur) {
	len[pcur]=pr-pl+1;
	if (pl==pr) {
		scanf("%lld",sumTree+pcur);
		return;
	}
	int pm=(pl+pr)>>1;
	Build(pl,pm,pcur<<1);
	Build(pm+1,pr,pcur<<1|1);
	sumTree[pcur]=sumTree[pcur<<1]+sumTree[pcur<<1|1];
}

void UpdateArea(int posl,int posr,int data,int pl,int pr,int pcur) { //區間修改（p[posl,posr]+=data）
	if (posl<=pl&&pr<=posr) {
		sumTree[pcur]+=data*len[pcur];
		lazy[pcur]+=data;
		return;
	}
	PushDown(pcur);
	int pm=(pl+pr)>>1;
	if(posl<=pm)UpdateArea(posl,posr,data,pl,pm,pcur<<1);
	if(posr>pm)UpdateArea(posl,posr,data,pm+1,pr,pcur<<1|1);
	sumTree[pcur]=sumTree[pcur<<1]+sumTree[pcur<<1|1];
}

ll sumQuery(int posl,int posr,int pl,int pr,int pcur) {
	if (posl<=pl&&pr<=posr)
		return sumTree[pcur];
    PushDown(pcur);
	int pm=(pl+pr)>>1;
	ll ans=0;
	if(posl<=pm)ans+=sumQuery(posl,posr,pl,pm,pcur<<1);
	if(posr>pm)ans+=sumQuery(posl,posr,pm+1,pr,pcur<<1|1);
	return ans;
}

int main() {
	int n,q,pl,pr,data;
	char t;
    scanf("%d %d",&n,&q);

    Build(1,n,1);

    while(q--){
        getchar();
        t=getchar();
        if(t=='Q'){
            scanf("%d %d",&pl,&pr);
            printf("%lld\n",sumQuery(pl,pr,1,n,1));
        }
        else{
            scanf("%d %d %d",&pl,&pr,&data);
            UpdateArea(pl,pr,data,1,n,1);
        }
    }

	return 0;
}