A Simple Problem with Integers POJ

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
#include<list>
#include<math.h>
#include<vector>
#include<stack>
#include<string>
#include<stdio.h>

using namespace std;
typedef long long LL;
const int MAXN = 1e5 + 10;
LL a[MAXN],st[MAXN << 2];
LL add[MAXN << 2];
void pushup(int o) {
    st[o] = st[o << 1] + st[o << 1 | 1];
}
void build(int o,int l,int r) {
    if (l == r) st[o] = a[l];
    else {
        int m = (l + r) >> 1;
        build(o << 1, l, m);
        build(o << 1 | 1, m + 1, r);
        pushup(o);
    }
}
void pushdown(int o,int l,int r) {
    if(add[o]) {
        add[o << 1] += add[o];
        add[o << 1 | 1] += add[o];
        int m = (l + r) >> 1;
        st[o << 1] += add[o] * (m - l + 1);
        st[o << 1 | 1] += add[o] * (r - m);
        add[o] = 0;
    }
}

LL query(int o,int l,int r,int ql,int qr) {
    if(ql <= l && r <= qr) return st[o];
    pushdown(o,l,r);
    int m = (l + r) >> 1;
    LL ans = 0;
    if(ql <= m) ans += query(o << 1, l, m, ql, qr);
    if(qr >= m + 1) ans += query(o << 1 | 1, m + 1, r, ql, qr);
    return ans;
}

void update(int o,int l,int r,int ql,int qr,LL addv) {
    if(ql <= l && r <= qr) {
        add[o] += addv;
        st[o] += addv * (r - l + 1);
        return;
    }
    pushdown(o,l,r);
    int m = (l + r) >> 1;
    if(ql <= m) update(o << 1,l,m,ql,qr,addv);
    if(qr >= m + 1) update(o << 1 | 1,m + 1,r,ql,qr,addv);
    pushup(o);
}


int main() {
    int n,q;
    scanf("%d %d",&n,&q);
    for (int i = 1; i <= n ; i++)
        scanf("%lld",&a[i]);
    build(1,1,n);
    char s[10];
    int x,y;
    LL add;
    while(q--) {
        scanf("%s",s);
        if(s[0] == 'Q') {
            scanf("%d %d",&x,&y);
            LL ans = query(1,1,n,x,y);
            printf("%lld
",ans);
        }
        else {
            scanf("%d %d %lld",&x,&y,&add);
            update(1,1,n,x,y,add);
        }
    }
}