POJ 3468 线段树

链接：

http://poj.org/problem?id=3468

题解：

就是普通的线段树区间更新，区间求和

代码：

#include <map>
#include <set>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mp make_pair
#define lson l,m,rt<<1  
#define rson m+1,r,rt<<1|1 
typedef long long ll;
typedef vector<int> VI;
typedef pair<int, int> PII;
const ll MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const int MAXN = 1e5 + 7;
// head

ll n, q;
ll tree[MAXN << 2], lazy[MAXN << 2];

void pushup(ll rt) {
    tree[rt] = tree[rt << 1] + tree[rt << 1 | 1];
}

void pushdown(ll rt, ll m) {
    if (lazy[rt] != 0) {
        tree[rt << 1] += lazy[rt] * (m - (m >> 1));
        tree[rt << 1 | 1] += lazy[rt] * (m >> 1);
        lazy[rt << 1] += lazy[rt];
        lazy[rt << 1 | 1] += lazy[rt];
        lazy[rt] = 0;
    }
}

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

void update(ll L, ll R, ll x, ll l, ll r, ll rt) {
    if (L <= l && r <= R) {
        tree[rt] += (r - l + 1)*x;
        lazy[rt] += x;
        return;
    }
    pushdown(rt, r - l + 1);
    ll m = (l + r) >> 1;
    if (L <= m) update(L, R, x, lson);
    if (R > m) update(L, R, x, rson);
    pushup(rt);
}

ll query(ll L, ll R, ll l, ll r, ll rt) {
    if (L <= l && r <= R) return tree[rt];
    pushdown(rt, r - l + 1);
    ll m = (l + r) >> 1;
    ll ret = 0;
    if (L <= m) ret += query(L, R, lson);
    if (R > m) ret += query(L, R, rson);
    return ret;
}

int main() {
    cin >> n >> q;
    build(1, n, 1);
    while (q--) {
        char ch;
        ll a, b, c;
        scanf("
%c", &ch);
        if (ch == 'C') {
            scanf("%lld%lld%lld", &a, &b, &c);
            update(a, b, c, 1, n, 1);
        }
        else {
            scanf("%lld%lld", &a, &b);
            printf("%lld
", query(a, b, 1, n, 1));
        }
    }
    return 0;
}