AcWing：108. 奇数码问题（归并排序 + 逆序数）

#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

const int maxn = 3e5+7;

typedef long long ll;

int arr[maxn];
int b[maxn];
ll cnt;

void merge_sort(int l, int mid, int r) {
    int i = l, j = mid + 1;
    int k = 0;
    while(i <= mid || j <= r) {
        if(j > r || (i <= mid && arr[i] <= arr[j])) {
            b[k++] = arr[i++];
        } else {
            cnt += mid - i + 1;
            b[k++] = arr[j++];
        }
    }
    for(int i = 0; i < k; i++) {
        arr[l + i] = b[i];
    }
}

void merge(int l, int r) {
    if(l < r) {
        int mid = (l + r) >> 1;
        merge(l, mid);
        merge(mid + 1, r);
        merge_sort(l, mid, r);
    }
}

void fun(ll &sum, int n) {
    int k = 0;
    for(int i = 1; i <= n * n; i++) {
        int x;
        scanf("%d", &x);
        if(x != 0) {
            arr[++k] = x;
        }
    }
    cnt = 0;
    merge(1, k);
    sum = cnt;
}

int main() {
    int n;
    while(~scanf("%d", &n)) {
        ll sum1, sum2;
        fun(sum1, n);
        fun(sum2, n);
        if((long long)abs(sum1 - sum2) % 2) {
            printf("NIE\n");
        } else {
            printf("TAK\n");
        }
    }
    return 0;
}