ACM学习历程—HDU 2795 Billboard(线段树)

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <string>
#include <algorithm>
#define LL long long

using namespace std;

int h, w, n;

//线段树
//区间某点增值，求区间最大值
const int maxn = 200005;
struct node
{
    int lt, rt;
    int val;
}tree[4*maxn];

//向上更新
void pushUp(int id)
{
    tree[id].val = max(tree[id<<1].val, tree[id<<1|1].val);
}

//建立线段树
void build(int lt, int rt, int id)
{
    tree[id].lt = lt;
    tree[id].rt = rt;
    tree[id].val = 0;//每段的初值，根据题目要求
    if (lt == rt)
    {
        tree[id].val = w;
        return;
    }
    int mid = (lt + rt) >> 1;
    build(lt, mid, id<<1);
    build(mid + 1, rt, id<<1|1);
    pushUp(id);
}

//查询某段区间内的符合p的
int query(int lt, int rt, int id, int p)
{
    if (tree[id].val < p)
        return -1;
    if (tree[id].lt == tree[id].rt)
    {
        tree[id].val -= p;
        return tree[id].lt;
    }
    int tmp;
    tmp = query(lt, rt, id<<1, p);
    if (tmp != -1)
    {
        pushUp(id);
        return tmp;
    }
    tmp = query(lt, rt, id<<1|1, p);
    pushUp(id);
    return tmp;
}

void work()
{
    int k, ans;
    int len = min(h, n);
    build(1, len, 1);
    for (int i = 0; i < n; ++i)
    {
        scanf("%d", &k);
        ans = query(1, len, 1, k);
        printf("%d\n", ans);
    }
}

int main()
{
    //freopen("test.in", "r", stdin);
    while (scanf("%d%d%d", &h, &w, &n) != EOF)
    {
        work();
    }
    return 0;
}