树状数组练习 POJ-2352 Stars

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 题目链接

#include <stdio.h>
#include <string.h>

#define N 32010

int t[N];

int ans[N];

int lowbit(int x)
{
    return x & (-x);
}

int get_sum(int k)
{
    int sum = 0;
    while (k > 0)
    {
        sum += t[k];
        k -= lowbit(k);
    }
    return sum;
}

void update(int k, int delta)
{
    while (k <= N)
    {
        t[k] += delta;
        k += lowbit(k);
    }
}

int main()
{
    int n;
    
    while (scanf("%d", &n) != EOF)
    {
        int x, y;
        memset(t, 0, sizeof(int) * N);
        memset(ans, 0, sizeof(int) * N);
        for (int i = 0; i < n; i++)
        {
            scanf("%d%d", &x, &y);
            ans[get_sum(x + 1)]++;
            update(x + 1, 1);
        }
        
        for (int i = 0; i < n; i++)
        {
            printf("%d\n", ans[i]);
        }
    }
    
    return 0;
}