Bear Limak has n colored balls, arranged in one long row. Balls are numbered 1 through n, from left to right. There are n possible colors, also numbered 1 through n. The i-th ball has color ti.
For a fixed interval (set of consecutive elements) of balls we can define a dominant color. It's a color occurring the biggest number of times in the interval. In case of a tie between some colors, the one with the smallest number (index) is chosen as dominant.
There are non-empty intervals in total. For each color, your task is to count
the number of intervals in which this color is dominant.
The first line of the input contains a single integer n (1 ≤ n ≤ 5000) — the number of balls.
The second line contains n integers t1, t2, ..., tn (1 ≤ ti ≤ n) where ti is the color of the i-th ball.
Print n integers. The i-th of them should be equal to the number of intervals where i is a dominant color.
4 1 2 1 2
7 3 0 0
3 1 1 1
6 0 0
In the first sample, color 2 is dominant in three intervals:
- An interval [2, 2] contains one ball. This ball's color is 2 so it's clearly a dominant color.
- An interval [4, 4] contains one ball, with color 2 again.
- An interval [2, 4] contains two balls of color 2 and one ball of color 1.
There are 7 more intervals and color 1 is dominant in all of them.
题目大意:
现在有N个数排咧,每一个数表示一种颜色。
对于区间【l,r】来讲,主色调就是最多出现次数的那个颜色,如果多种颜色出现次数都是最多的,那么取编号最小的作为主色调。
问每种颜色作为主色调的次数。
思路:
观察到数据范围N并不大,我们O(n^2)来枚举区间的左右端点。
接下来的任务就是对于区间【l,r】判定主色调。
如果直接暴力判断,那么需要O(n^3)的时间复杂度。
其实这个题就是一个脑筋急转弯的题。
我们在确定了区间左端点,而枚举右端点的过程中,r是逐渐增加的,其实在枚举右端点的过程中,我们就可以维护主色调的编号了。。
Ac代码:
#include<stdio.h>
#include<string.h>
using namespace std;
int a[5005];
int vis[5005];
int ans[5005];
int main()
{
int n;
while(~scanf("%d",&n))
{
memset(vis,0,sizeof(vis));
memset(ans,0,sizeof(ans));
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
}
for(int i=1;i<=n;i++)
{
int maxn=0;
int color=-1;
memset(vis,0,sizeof(vis));
for(int j=i;j<=n;j++)
{
vis[a[j]]++;
if(vis[a[j]]>maxn)maxn=vis[a[j]],color=a[j];
if(vis[a[j]]==maxn)
{
if(a[j]<color)color=a[j];
}
ans[color]++;
}
}
for(int i=1;i<=n;i++)printf("%d ",ans[i]);
}
}