POJ 3468 A Simple Problem with Integers 【线段树】

题目链接

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

思路

线段树 区间更新 模板题 在赋初始值的时候，按点更新区间就可以

AC代码

#include <cstdio>
#include <cstring>
#include <ctype.h>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <map>
#include <stack>
#include <set>
#include <numeric>
#include <sstream>

using namespace std;
typedef long long LL;

const double PI = 3.14159265358979323846264338327;
const double E = 2.718281828459;
const double eps = 1e-6;

const int MAXN = 0x3f3f3f3f;
const int MINN = 0xc0c0c0c0;
const int maxn = 1e5 + 5;
const int MOD = 1e9 + 7;

int n, q;
LL anssum;

struct Node
{
    LL l, r;
    LL addv, sum;
}tree[maxn << 2];

void maintain(int id)
{
    if (tree[id].l >= tree[id].r)
        return;
    tree[id].sum = tree[id << 1].sum + tree[id << 1 | 1].sum;
}

void pushdown(int id)
{
    if (tree[id].l >= tree[id].r)
        return;
    if (tree[id].addv)
    {
        int tmp = tree[id].addv;
        tree[id << 1].addv += tmp;
        tree[id << 1 | 1].addv += tmp;
        tree[id << 1].sum += (tree[id << 1].r - tree[id << 1].l + 1) * tmp;
        tree[id << 1 | 1].sum += (tree[id << 1 | 1].r - tree[id << 1 | 1].l + 1) * tmp;
        tree[id].addv = 0;
    }
}

void build(int id, LL l, LL r)
{
    tree[id].l = l;
    tree[id].r = r;
    tree[id].addv = 0;
    tree[id].sum = 0;
    if (l == r)
    {
        tree[id].sum = 0;
        return;
    }
    LL mid = (l + r) >> 1;
    build(id << 1, l, mid);
    build(id << 1 | 1, mid + 1, r);
    maintain(id);
}

void updateAdd(int id, LL l, LL r, LL val)
{
    if (tree[id].l >= l && tree[id].r <= r)
    {
        tree[id].addv += val;
        tree[id].sum += (tree[id].r - tree[id].l + 1) * val;
        return;
    }
    pushdown(id);
    LL mid = (tree[id].l + tree[id].r) >> 1;
    if (l <= mid)
        updateAdd(id << 1, l, r, val);
    if (mid < r)
        updateAdd(id << 1 | 1, l, r, val);
    maintain(id);
}

void query(int id, LL l, LL r)
{
    if (tree[id].l >= l && tree[id].r <= r)
    {
        anssum += tree[id].sum;
        return;
    }
    pushdown(id);
    LL mid = (tree[id].l + tree[id].r) >> 1;
    if (l <= mid)
        query(id << 1, l, r);
    if (mid < r)
        query(id << 1 | 1, l, r);
    maintain(id);
}

int main()
{
    scanf("%d %d", &n, &q);
    build(1, 1, n);
    for (LL i = 1; i <= n; i++)
    {
        LL num;
        cin >> num;
        updateAdd(1, i, i, num);
    }
    char id;
    LL x, y;
    LL val;
    while (q--)
    {
        scanf(" %c", &id);
        if (id == 'C')
        {
            scanf("%lld %lld %lld", &x, &y, &val);
            updateAdd(1, x, y, val);
        }
        else if (id == 'Q')
        {
            scanf("%lld %lld", &x, &y);
            anssum = 0;
            query(1, x, y);
            cout << anssum << endl;
        }
    }
}