#include <bits/stdc++.h>
#ifdef _WIN32
#	define getchar_unlocked getchar
#endif
using namespace std;

inline int read() {
	int f = 0, x = 0;
	char c = getchar();
	while (!isdigit(c)) c ^= c == '-', c = getchar_unlocked();
	while (isdigit(c)) x = (x << 3) + (x << 1) + (c ^ 48), c = getchar_unlocked();
	return f ? -x : x;
}

int n, m;
int a[110][110];
int f[110][110][2][2];
const int cx[4] = {0, -1, 0, 1};
const int cy[4] = {-1, 0, 1, 0};
const int dx[4] = {1, 1, 0, 0};
const int dv[4] = {0, 0, 1, 1};
const int dy[4] = {0, 1, 0, 1};
const int ex[4] = {0, 0, 1, 3};

int main() {
	cin >> m >> n;
	memset(a, 0xff, sizeof(a));
	memset(f, 0x7f, sizeof(f));
	for (int i = 1; i <= n; i++)
		a[read()][read()] = read();
	f[1][1][a[1][1]][0] = 0;
	
	for (int i = 1; i <= m; i++)
		for (int j = 1; j <= m; j++)
			for (int k = 1; k <= m; k++)
				for (int l = 0; l < 4; l++)
					if (a[j][k] == 1)
						for (int x = 0; x < 4; x++)
							f[j][k][1][0] = min(f[j][k][1][0], f[j + cx[l]][k + cy[l]][dx[x]][dy[x]] + ex[x]);
					else if (a[j][k] == 0)
						for (int x = 0; x < 4; x++)
							f[j][k][0][0] = min(f[j][k][0][0], f[j + cx[l]][k + cy[l]][dv[x]][dy[x]] + ex[x]);
					else
						for (int x = 0; x < 2; x++)
							f[j][k][x][1] = min(min(f[j][k][x][1], f[j][k][x][0] + 2), min(f[j + cx[l]][k + cy[l]][x][0] + 2, f[j + cx[l]][k + cy[l]][!x][0] + 3));
	int mni = f[m][m][1][0];
	for (int i = 1; i < 4; i++)
		mni = min(mni, f[m][m][dx[i]][dy[i]]);
	cout << (mni == 0x7f7f7f7f ? -1 : mni);
}

输入：

3 5
1 1 0
1 3 1
2 2 1
2 3 0
3 1 1

本地输出：

6

洛谷 IDE 输出：

6

提交上去：

[Testp#3] Wrong Answer.wrong answer On line 1 column 1, read -, expected 6.

提交输出（理论上）：

-1

为甚么呢？