PKU 2352 - Stars (树状数组)

题意

统计每个level的星星个数。每个星星的level是X、Y坐标都比他小的星星个数。

思路

这题的坐标都帮我们排序好了,直接用树状数组统计x即可。

代码

#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <cmath>
#define LL long long
#define SZ(x) (int)x.size()
#define Lowbit(x) ((x) & (-x))
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define LC rt << 1, l, mid
#define RC rt << 1|1, mid + 1, r
#define LRT rt << 1
#define RRT rt << 1|1
#define BitCount(x) __builtin_popcount(x)
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
using namespace std;
const int MAXN = 35000 + 10;
const int MOD = 1e9 + 7;
 
typedef pair<int, int> pii;
typedef vector<int>::iterator viti;
typedef vector<pii>::iterator vitii;
 
int C[MAXN], n, val[MAXN];
 
int Sum(int x)
{
    int ret = 0;
    while (x > 0)
    {
        ret += C[x];
        x -= Lowbit(x);
    }
    return ret;
}
 
void Update (int x)
{
    while (x < MAXN)
    {
        C[x]++;
        x += Lowbit(x);
    }
}
 
int main()
{
    //ROP;
    int i, j;
    scanf("%d", &n);
    for (i = 0; i < n; i++)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        x++;
        int ans = Sum(x);
        val[ans]++;
        Update(x);
    }
    for (i = 0; i < n; i++)
        if (val[i]) printf("%d\n", val[i]);
        else printf("0\n");
    return 0;
}

Powered by Jekyll and Theme by solid