线段树：优雅的分块暴力

区间修改（单点修改），区间查询

POJ3468

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
const int maxn = 1e6+10;
using namespace std;
typedef long long ll;

ll aa[maxn], ans;
struct node{
    ll a, b, len;
    ll sum;
    ll lazy;
};

node tree[maxn*4];
void pushup(int rt){tree[rt].sum = tree[rt<<1].sum+tree[rt<<1|1].sum;return;}
int cnt  =1;

void build(ll a, ll b, int num){
    cnt = max(num, cnt);

        tree[num].a = a;
        tree[num].b = b;
        tree[num].lazy = 0;
        tree[num].len = (b-a+1);
        if(a == b){tree[num].sum = aa[a];}
        else{
        int mid = (a+b)>>1;
        build(a, mid, num<<1);
        build(mid+1, b, (num<<1)+1);
        pushup(num);

        }
}

void pushdown(int rt){
    if(tree[rt].lazy){
        tree[rt<<1].lazy+=tree[rt].lazy;
        tree[rt<<1|1].lazy+=tree[rt].lazy;

        tree[rt<<1].sum+=tree[rt<<1].len*tree[rt].lazy;
        tree[rt<<1|1].sum+=tree[rt<<1|1].len*tree[rt].lazy;
        tree[rt].lazy = 0;
    }
}

/*345各加3，+6不是+9？？？*/
void query(ll a, ll b, int num){
    if(a>tree[num].b||tree[num].a>b) return;
    if(tree[num].a>=a&&tree[num].b<=b){
        pushdown(num);
        ans+=tree[num].sum;
        return;
    }
    pushdown(num);

    query(a, b, num<<1|1);
    query(a, b, (num<<1));

    pushup(num);
}

void add(ll a, ll b, ll val, int num){
    if(a>tree[num].b||tree[num].a>b) return;
    if(tree[num].a>=a&&tree[num].b<=b){
        tree[num].sum+=tree[num].len*val;
        tree[num].lazy+=val;
        return ;
    }
    pushdown(num);  //向下更新时先pushdown

    add(a, b, val, num<<1);
    add(a, b, val, num<<1|1);
    pushup(num); //更新
}

int main(){
    int n, m;
    cin>>n>>m;
    for(int i = 1; i <= n; i++){
        scanf("%lld", &aa[i]);
    }

    build(1, n, 1);//从一开始建树

    /*for(int i = 1; i <= cnt; i++){
        printf("%d  ;%d  %d :sum : %d\n", i, tree[i].a, tree[i].b, tree[i].sum);
    }*/
    ll x, y, z;
    char ch;
    for(int i = 0; i < m; i++){
        //scanf("%c %d%d\n", &ch, &x, &y);
        cin>>ch>>x>>y;
        if(ch == 'Q'){
            ans = 0;
            query(x, y, 1);
            printf("%lld\n", ans);
            //getchar();
        }
        else{
            scanf("%lld\n", &z);
            add(x, y, z, 1);
           /* for(int i = 1; i <= cnt; i++){
        printf("%d  ;%d  %d :sum : %d\n", i, tree[i].a, tree[i].b, tree[i].sum);
    }*/
        }
    }

    return 0;
}