A Simple Problem with Integers POJ - 3468(线段树，区间更新)

#include <stdio.h>
#include <algorithm>
using namespace std;
const int maxn=1e5+100;
struct node{int l, r;long long sum, lazy;
}tr[maxn<<2];
long long a[maxn];
void updown(int m){tr[m].sum=tr[m<<1].sum+tr[m<<1|1].sum;
}
void build(int m, int l, int r){tr[m].l=l;tr[m].r=r;tr[m].lazy=0;if(l==r){scanf("%lld", &tr[m].sum);return;}int mid=(l+r)>>1;build(m<<1, l, mid);build(m<<1|1, mid+1, r);updown(m);
}
void pushdown(int m){if(tr[m].lazy){tr[m].sum+=(tr[m].r-tr[m].l+1)*tr[m].lazy;if(tr[m].l==tr[m].r){tr[m].lazy=0;return;}tr[m<<1].lazy+=tr[m].lazy;tr[m<<1|1].lazy+=tr[m].lazy;tr[m].lazy=0;}
}
void updata(int m, int l, int r, long long val){pushdown(m);if(tr[m].l>r||tr[m].r<l) return;if(tr[m].l>=l&&tr[m].r<=r){tr[m].sum+=(tr[m].r-tr[m].l+1)*val;if(tr[m].r==tr[m].l) return;tr[m<<1].lazy+=val;tr[m<<1|1].lazy+=val;return;}updata(m<<1, l, r, val);updata(m<<1|1, l, r, val);updown(m);
}
long long query(int m, int l, int r){pushdown(m);if(tr[m].l>r||tr[m].r<l) return 0;if(tr[m].l>=l&&tr[m].r<=r) return tr[m].sum;return query(m<<1, l, r)+query(m<<1|1, l, r);updown(m);
}
int main(){int N, Q;while(~scanf("%d%d", &N, &Q)){build(1, 1, N);//print(1);while(Q--){char op[5];scanf("%s", op);if(op[0]=='C'){int a, b, c;scanf("%d%d%d", &a, &b, &c);updata(1, a, b, c);}else{int a, b;scanf("%d%d", &a, &b);printf("%lld\n", query(1, a, b));}//print(1);}}return 0;
}