[C++知识库]CSP 202012-2 期末预测之最佳阈值 C语言满分答案

CSP 202012-2 期末预测之最佳阈值 C语言满分答案

#include <stdio.h>
#include <stdlib.h>



int cmp(const void* _a , const void* _b)//小到大
{
    int* a = (int*)_a;
    int* b = (int*)_b;
    return *a - *b;
}

main()
{


    int m;
    int i,j,k;
    int out=0,best_count=0;
    int arr_every_count=0;
    int tmp = 0,how_continuity=0;
    scanf("%d",&m);
    int arr_everysmaller_count[m];
    int arr_everybigger_count[m];
    int arr[m][2];

	for(i=0;i<m;i++) scanf("%d %d",&arr[i][0],&arr[i][1]);
    qsort(arr,m,sizeof(arr[0]),cmp);//按安全值排序从小到大

    arr_every_count = 0;
    for(i=m-1;i>=0;i--)//从后往前将每个阀值之后正确的数量计算出来
    {
        if(arr[i][1]==1)arr_every_count++;
        arr_everybigger_count[i] = arr_every_count;

        if(tmp==arr[i][0])//下面几行是为了有重复阀值时能够保证稳定性
        {
            how_continuity++;
        }
        if(how_continuity>0&&tmp!=arr[i][0])
        {
            for(j=i+1;j<=i+how_continuity;j++)
            {
                arr_everybigger_count[j] = arr_everybigger_count[i+1];
            }
            how_continuity=0;
        }
        tmp = arr[i][0];
    }
    arr_every_count = 0;
    tmp = 0;
    for(i=0;i<m;i++)//从前往后将每个阀值之前正确的数量计算出来
    {
        arr_everysmaller_count[i] = arr_every_count;
        if(arr[i][1]==0)arr_every_count++;

        if(tmp==arr[i][0])//下面几行是为了有重复阀值时能够保证稳定性
        {
            how_continuity++;
        }
        if(how_continuity>0&&tmp!=arr[i][0])
        {
            for(j=i-1;j>=i-how_continuity-1;j--)
            {
                arr_everysmaller_count[j] = arr_everysmaller_count[i-how_continuity-1];
            }
            how_continuity=0;
        }
        tmp = arr[i][0];
    }

    for(i=0;i<m;i++)//相加计算结果
    {
        int count = arr_everysmaller_count[i] + arr_everybigger_count[i];
        if(count>=best_count)
        {
            if(count==best_count)
            {
                if(out<arr[i][0])
                {
                    out = arr[i][0];
                }
            }else
            {
                out = arr[i][0];
                best_count = count;
            }
        }
    }
    printf("%d",out);

    return 0;
}