這題就算演算法對了,我還是TLE十幾次.

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;

int m, n, s[1000010], ct, tmp[1000010];

inline void merge(int l, int r) {
    if (l == r) return;
    int mid = l + r >> 1;
    merge(l, mid);
    merge(mid 
 
+ 1, r);
    int i = l, j = mid + 1;
    for (register int k = l; k <= r; k++)
        if (j > r || i <= mid && s[i] <= s[j])
            tmp[k] = s[i++];
        else
            tmp[k] = s[j++], ct += mid - i + 1;
    for (register int i = l; i <= r; i++) s[i] = tmp[i];
}

int
 
 main() {
    ios::sync_with_stdio(false);    // 就算這樣也不行
    cin.tie(0), cout.tie(0);
    while (cin >> m >> n) {
        if (!m && !n) return 0;

        ct = 0;
        int linex = 0, b;
        int k = 0;
        for (register int i = 1; i <= m; i++)
            for (register int j = 1
 
; j <= n; j++) {
                cin >> b;
                if (!b)
                    linex = m - i;
                else
                    s[++k] = b;
            }

        merge(1, k);

        if (n & 1) {
            if (ct & 1)
                puts("NO");
            else
                puts("YES");
        } else if ((linex ^ ct) & 1)
            puts("NO");
        else
            puts("YES");
    }

    return 0;
}

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;

int m, n, s[1000010], ct, tmp[1000010];

inline void merge(int l, int r) {
    if (l == r) return;
    int mid = l + r >> 1;
    merge(l, mid);
    merge(mid + 1, r);
    int i = l, j = mid + 1;
    for (register int k = l; k <= r; k++)
        if (j > r || i <= mid && s[i] <= s[j])
            tmp[k] = s[i++];
        else
            tmp[k] = s[j++], ct += mid - i + 1;
    for (register int i = l; i <= r; i++) s[i] = tmp[i];
}

int main() {
    while (scanf("%d%d", &m, &n)) {
        if (!m && !n) return 0;

        ct = 0;
        int linex = 0, b;
        int k = 0;
        for (register int i = 1; i <= m; i++)
            for (register int j = 1; j <= n; j++) {
                scanf("%d", &b);
                if (!b)
                    linex = m - i;
                else
                    s[++k] = b;
            }

        merge(1, k);

        if (n & 1) {
            if (ct & 1)
                puts("NO");
            else
                puts("YES");
        } else if ((linex ^ ct) & 1)
            puts("NO");
        else
            puts("YES");
    }

    return 0;
}

十分頭疼.