A Simple Problem with Integers POJ

思路：线段树，区间更新，区间查找

#include<iostream>
#include<vector>
#include<string>
#include<cmath>
#include<set>
#include<algorithm>
#include<cstdio>
#include<map>
#include<cstring>
#include<list>

#define MAXSIZE 100010

using namespace std;

long long tree[4*MAXSIZE];
long long lz[4*MAXSIZE];
int N, Q;

void init()
{
    memset(tree, 0, sizeof(tree));
    memset(lz, 0, sizeof(lz));
}

void build(int node, int l, int r)
{
    if(l == r)
    {
        scanf("%lld", &tree[node]);
        return;
    }
    
    int mid = (l+r)/2;
    build(node*2, l, mid);
    build(node*2+1, mid+1, r);
    
    tree[node] = tree[node*2] + tree[node*2+1];
}

void push_down(int node, int l, int r)
{
    if(lz[node])
    {
        int mid = (l+r)/2;
        lz[node*2] += lz[node];
        lz[node*2+1] += lz[node];
        tree[node*2] += (mid-l+1)*lz[node];
        tree[node*2+1] += (r-mid)*lz[node];
        lz[node] = 0;
    }
}

void update_range(int node, int l, int r, int L, int R, int add)
{
    if(l <= L && r >= R)
    {
        lz[node] += add;
        tree[node] += (R-L+1)*add;
        return;
    }
    push_down(node, L, R);
    int mid = (L+R)/2;
    if(mid >= l)
        update_range(node*2, l, r, L, mid, add);
    if(mid < r)
        update_range(node*2+1, l, r, mid+1, R, add);
    tree[node] = tree[node*2] + tree[node*2+1];
}

long long query_range(int node, int l, int r, int L, int R)
{
    if(l <= L && r >= R)
    {
        return tree[node];
    }
    push_down(node, L, R);
    int mid = (L+R)/2;
    long long sum = 0;
    if(mid >= l)
        sum += query_range(node*2, l, r, L, mid);
    if(mid < r)
        sum += query_range(node*2+1, l, r, mid+1, R);
    
    return sum;
}



int main()
{    
    scanf("%d%d", &N, &Q);
    init();
    build(1, 1, N);
    while(Q--)
    {
        char ch;
        scanf(" %c", &ch);
        if(ch == 'Q')
        {
            int a, b;
            scanf("%d%d", &a, &b);
            printf("%lld
", query_range(1, a, b, 1, N));
        }
        else if(ch == 'C')
        {
            int a, b, c;
            scanf("%d%d%d", &a, &b, &c);
            update_range(1, a, b, 1, N, c);
        }
    }
    

    return 0;
}