线段树模板(二)——成段更新 + POJ 3468 A Simple Problem with Integers

/*2266ms,4508KB*/

#include <cstdio>
#include <algorithm>
using namespace std;
#define lson l , m , rt << 1
#define rson m + 1 , r , rt << 1 | 1
#define root 1, N, 1
#define LL long long
const int maxn = 100000;

LL sum[maxn << 2], add[maxn << 2];

inline void pushup(int rt)
{
	sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];
}

inline void pushdown(int rt, int m)
{
	if (add[rt])
	{
		add[rt << 1] += add[rt];
		add[rt << 1 | 1] += add[rt];///更新左右子区间add
		sum[rt << 1] += add[rt] * (m - (m >> 1));
		sum[rt << 1 | 1] += add[rt] * (m >> 1);///平分父节点add，更新左右子区间和
		add[rt] = 0;///父节点add清零
	}
}

void build(int l, int r, int rt)
{
	add[rt] = 0;
	if (l == r)
	{
		scanf("%lld", &sum[rt]);
		return;
	}
	int m = (l + r) >> 1;
	build(lson);
	build(rson);
	pushup(rt);
}

void update(int ql, int qr, int c, int l, int r, int rt)
{
	if (ql <= l && r <= qr)
	{
		add[rt] += c;///存至此，不再往下更新
		sum[rt] += (LL)c * (r - l + 1);
		return;
	}
	pushdown(rt , r - l + 1);///用父节点add往下细分计算 
	int m = (l + r) >> 1;
	if (ql <= m) update(ql, qr, c, lson);
	if (qr > m) update(ql, qr, c, rson);
	pushup(rt);
}

LL query(int ql, int qr, int l, int r, int rt)
{
	if (ql <= l && r <= qr)
	{
		return sum[rt];
	}
	pushdown(rt , r - l + 1);///用父节点add往下细分计算 
	int m = (l + r) >> 1;
	LL ret = 0;
	if (ql <= m) ret += query(ql, qr, lson);
	if (qr > m) ret += query(ql, qr, rson);
	return ret;
}

int main()
{
	int N, Q, a, b, c;
	scanf("%d%d", &N, &Q);
	build(root);
	while (Q--)
	{
		getchar();
		if (getchar() == 'Q')
		{
			scanf("%d%d", &a, &b);
			printf("%lld\n", query(a, b, root));
		}
		else
		{
			scanf("%d%d%d", &a, &b, &c);
			update(a, b, c, root);
		}
	}
	return 0;
}