cf1556B B. Take Your Places!

Posted 2021-09-17 Jozky86

cf1556B B. Take Your Places!

题意：

有n个数，你可以将相邻两个数交换，使得奇偶性一样的数不相邻。问最少操作步数

题解：

最终排列无非是：奇，偶，奇…或者偶，奇，偶…
如果奇数>偶数，我们就按照第一个排，如果偶数＞奇数，我们就按照第二个排。如果两者相等，两种排列都测一遍，取较小值

代码：

// Problem: B. Take Your Places!
// Contest: Codeforces - Deltix Round, Summer 2021 (open for everyone, rated, Div. 1 + Div. 2)
// URL: https://codeforces.com/contest/1556/problem/B
// Memory Limit: 256 MB
// Time Limit: 1000 ms
// Data:2021-08-31 23:46:12
// By Jozky

#include <bits/stdc++.h>
#include <unordered_map>
#define debug(a, b) printf("%s = %d\\n", a, b);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> PII;
clock_t startTime, endTime;
//Fe~Jozky
const ll INF_ll= 1e18;
const int INF_int= 0x3f3f3f3f;
void read(){};
template <typename _Tp, typename... _Tps> void read(_Tp& x, _Tps&... Ar)
{
    x= 0;
    char c= getchar();
    bool flag= 0;
    while (c < '0' || c > '9')
        flag|= (c == '-'), c= getchar();
    while (c >= '0' && c <= '9')
        x= (x << 3) + (x << 1) + (c ^ 48), c= getchar();
    if (flag)
        x= -x;
    read(Ar...);
}
template <typename T> inline void write(T x)
{
    if (x < 0) {
        x= ~(x - 1);
        putchar('-');
    }
    if (x > 9)
        write(x / 10);
    putchar(x % 10 + '0');
}
void rd_test()
{
#ifdef LOCAL
    startTime= clock();
    freopen("in.txt", "r", stdin);
#endif
}
void Time_test()
{
#ifdef LOCAL
    endTime= clock();
    printf("\\nRun Time:%lfs\\n", (double)(endTime - startTime) / CLOCKS_PER_SEC);
#endif
}
const int maxn= 1e5 + 9;
int a[maxn];
int b[maxn];
int main()
{
    //rd_test();
    int t;
    read(t);
    while (t--) {
        int n;
        read(n);
        vector<int> q1; //奇数
        vector<int> q2; //偶数
        for (int i= 0; i < n; i++) {
            read(a[i]);
            if (a[i] % 2 == 1) //奇数
                q1.push_back(i);
            else
                q2.push_back(i);
        }
        if (n == 1)
            printf("0\\n");
        else if (abs((int)q1.size() - (int)q2.size()) > 1)
            printf("-1\\n");
        else if ((int)q1.size() > (int)q2.size()) {
            int pos= 0;
            ll sum= 0;
            for (int i= 0; i < q1.size(); i++) {
                sum+= abs(q1[i] - pos);
                pos+= 2;
            }
            printf("%lld\\n", sum);
        }
        else if ((int)q1.size() < (int)q2.size()) {
            int pos= 0;
            ll sum= 0;
            for (int i= 0; i < q2.size(); i++) {
                sum+= abs(q2[i] - pos);
                pos+= 2;
            }
            printf("%lld\\n", sum);
        }
        else if ((int)q1.size() == (int)q2.size()) {
            int pos= 0;
            ll sum= 0;
            for (int i= 0; i < q1.size(); i++) {
                sum+= abs(q1[i] - pos);
                pos+= 2;
            }
            pos= 0;
            ll sum2= 0;
            for (int i= 0; i < q2.size(); i++) {
                sum2+= abs(q2[i] - pos);
                pos+= 2;
            }
            printf("%lld\\n", min(sum, sum2));
        }
    }
    return 0;
    //Time_test();
}