再访数据结构

数据结构是我当年难以逾越的一道沟…
多年以后，先从最简单的线段树下手吧
写了一个 洛谷线段树的模板题 区间加 和 区间求和 很简单，算是留念吧

//
// Created by DELL on 2020/3/1.
//

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#define Maxn 100005
#define  LL long long
using namespace std;
struct Seg_Ment_Tree{
    int l,r,lazy; LL Sum;
}tre[Maxn << 2];

void Built(int now,int l ,int r) {
    tre[now].l = l,tre[now].r = r,tre[now].Sum = tre[now].lazy = 0;
    if(l == r) { scanf("%lld",&tre[now].Sum); return ; }
    int Mid = l + r >> 1;
    Built(now << 1,l,Mid);
    Built(now << 1 | 1,Mid + 1,r);
    tre[now].Sum = tre[now << 1].Sum + tre[now << 1 | 1].Sum;
}

inline void Pushdown(int now) {
    tre[now << 1].lazy += tre[now].lazy;
    tre[now << 1 | 1].lazy += tre[now].lazy;
    tre[now << 1].Sum += (tre[now << 1].r - tre[now << 1].l  + 1) * tre[now].lazy;
    tre[now << 1 | 1].Sum += (tre[now << 1 | 1].r - tre[now << 1 | 1].l  + 1) * tre[now].lazy;
    tre[now].lazy = 0;
    return ;
}

void Modify(int now,int l,int r,int val){
    if(l == tre[now].l && tre[now].r == r) {
        tre[now].Sum += (tre[now].r - tre[now].l + 1) * val;
        tre[now].lazy += val;
        return ;
    }
    if(tre[now].lazy ) Pushdown(now);
    int Mid = tre[now].l + tre[now].r >> 1;
    if(l > Mid) Modify(now << 1 | 1,l,r,val);
    else if(r <= Mid) Modify(now << 1,l,r,val);
    else { Modify(now << 1,l,Mid,val); Modify(now << 1 | 1,Mid + 1,r,val); }
    tre[now].Sum = tre[now << 1].Sum + tre[now << 1 | 1].Sum;
}

LL Query(int now,int l,int r) {
    if(l == tre[now].l && tre[now].r == r) return tre[now].Sum;
    int ret = 0;
    if(tre[now].lazy) Pushdown(now);
    int Mid = tre[now].l + tre[now].r >> 1;
    if(l > Mid)return Query(now << 1|1,l,r);
    else if(r <= Mid) return  Query(now << 1,l,r);
    else return Query(now << 1,l,Mid) + Query(now << 1 | 1,Mid + 1,r);
    //return ret;
}

int main(int argc,char* argv[]) {
    int val,l,r,n,m,opt; char ch;
    while(scanf("%d%d",&n,&m) == 2 && n) {
        Built(1,1,n);
        for(int i=1; i<=m; i++) {
            scanf("%d",&opt);
            if(opt == 1) {
                scanf("%d%d%d",&l,&r,&val);
                Modify(1,l,r,val);
            }
            if(opt == 2) {
                scanf("%d%d",&l,&r);
                printf("%lld\n",Query(1,l,r));
            }
        }
        break;
    }
    return 0;
}