Balanced Ternary String【Codeforces Round #531 (Div. 3)D】【贪心、构造】

题目链接

一道简单的构造，我们可以分成几个状态，因为所有的状态只有8个，所以，直接写每个状态即可，哎…… 被hack了…… 烦啊…… 谁让我写的好烂…… 好菜啊…… 呜呜呜

#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 3e5 + 7;
int N, num0, num1, num2, splay, head0, head1, head2, sum0, sum1, sum2;
char a[maxN];
int N_0[maxN], N_1[maxN], N_2[maxN];
int main()
{
    scanf("%d", &N);
    head0 = head1 = head2 = 1;
    num0 = num1 = num2 = 0;
    scanf("%s", a + 1);
    for(int i=1; i<=N; i++)
    {
        if(a[i] == '0') N_0[++num0] = i;
        else if(a[i] == '1') N_1[++num1] = i;
        else N_2[++num2] = i;
    }
    sum0 = num0;    sum1 = num1;    sum2 = num2;
    splay = N/3;    //平衡点的中间值
    if(sum0 == splay && sum1 == splay && sum2 == splay) { printf("%s\n", a+1); return 0; }
    if(sum0 > splay && sum1 <= splay && sum2 <= splay)  //001
    {
        for(int i=splay+1; i<=sum0; i++)
        {
            if(sum1 < splay)
            {
                a[N_0[i]] = '1';
                sum1++;
            }
            else
            {
                a[N_0[i]] = '2';
                sum2++;
            }
        }
        printf("%s\n", a+1); return 0;
    }
    if(sum0 <= splay && sum1 > splay && sum2 <= splay)  //010
    {
        int det = sum1 - splay;
        while(det--)
        {
            if(sum0 < splay)
            {
                a[N_1[head1++]] = '0';
                sum0++;
            }
            else
            {
                a[N_1[num1--]] = '2';
                sum2++;
            }
        }
        printf("%s\n", a+1); return 0;
    }
    if(sum0 > splay && sum1 > splay && sum2 <= splay)   //011
    {
        for(int i=splay+1; i<=sum0; i++)
        {
            a[N_0[i]] = '2';
        }
        for(int i=splay+1; i<=sum1; i++)
        {
            a[N_1[i]] = '2';
        }
        printf("%s\n", a+1); return 0;
    }
    if(sum0 <= splay && sum1 <= splay && sum2 > splay)  //100
    {
        int det = sum2 - splay;
        while(det--)
        {
            if(sum0 < splay)
            {
                a[N_2[head2++]] = '0';
                sum0++;
            }
            else
            {
                a[N_2[head2++]] = '1';
                sum1++;
            }
        }
        printf("%s\n", a+1); return 0;
    }
    if(sum0 > splay && sum1 <= splay && sum2 > splay)   //101
    {
        for(int i=splay+1; i<=sum0; i++)
        {
            a[N_0[i]] = '1';
        }
        int det = sum2 - splay;
        while(det--)
        {
            a[N_2[head2++]] = '1';
            sum1++;
        }
        printf("%s\n", a+1); return 0;
    }
    if(sum0 <= splay && sum1 > splay && sum2 > splay)   //110
    {
        int det = sum1 - splay;
        while(det--)
        {
            a[N_1[head1++]] = '0';
            sum0++;
        }
        det = sum2 - splay;
        while(det--)
        {
            a[N_2[head2++]] = '0';
            sum0++;
        }
        printf("%s\n", a+1); return 0;
    }
    return 0;
}