URAL 1028 Stars

URAL_1028

    将点排序后依次插入线段树，就可以将计算星星等级转化成区间求和的问题了，于是用线段树支持单点修改和区间求和即可。

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define MAXD 15010
#define MAXX 32010
struct Point
{
    int x, y;
}p[MAXD];
const int D = 32000;
int N, num[4 * MAXX], h[MAXD];
int cmp(const void *_p, const void *_q)
{
    Point *p = (Point *)_p, *q = (Point *)_q;
    if(p->y == q->y)
        return p->x < q->x ? -1 : 1;
    return p->y < q->y ? -1 : 1;
}
void init()
{
    int i, j, k;
    for(i = 0; i < N; i ++)
        scanf("%d%d", &p[i].x, &p[i].y);
    qsort(p, N, sizeof(p[0]), cmp);
    memset(num, 0, sizeof(num));
}
void update(int cur)
{
    num[cur] = num[cur << 1] + num[(cur << 1) | 1];
}
int Search(int cur, int x, int y, int s, int t)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    if(x >= s && y <= t)
        return num[cur];
    if(mid >= t)
        return Search(ls, x, mid, s, t);
    else if(mid + 1 <= s)
        return Search(rs, mid + 1, y, s, t);
    else
        return Search(ls, x, mid, s, t) + Search(rs, mid + 1, y, s, t);
}
void refresh(int cur, int x, int y, int k)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    if(x == y)
    {
        ++ num[cur];
        return ;
    }
    if(k <= mid)
        refresh(ls, x, mid, k);
    else
        refresh(rs, mid + 1, y, k);
    update(cur);
}
void solve()
{
    int i, j, k;
    memset(h, 0, sizeof(h));
    for(i = 0; i < N; i ++)
    {
        k = Search(1, 0, D, 0, p[i].x);
        ++ h[k];
        refresh(1, 0, D, p[i].x);
    }
    for(i = 0; i < N; i ++)
        printf("%d\n", h[i]);
}
int main()
{
    while(scanf("%d", &N) == 1)
    {
        init();
        solve();
    }
    return 0;
}