寻路问题: $N * N$ 矩阵，其中 $0$ 是表示可以走的， $1$ 表示无法走，矩阵由二维数组表示，左上角是入口，右下角是出口，只能横着走和竖着走，要求找出最短路径。

#include<bits/stdc++.h>
using namespace std;

int mymax = 10000;
int f[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
int a[20][20], v[20][20], v1[20][20];
int l = 1;
int n; //矩阵的规模
bool check(int x1, int y1) {
	if (x1 < 0 || x1 >= n || ___(1)___ ) return false;
	if (a[x1][y1] == 1 || ___(2)___ ) return false;
	return true;
}

void dfs(int x, int y) {
	if (x == n - 1 && y == n - 1) {
		if (l < mymax) {
			mymax = l;
			memcpy(v1, v, sizeof(v1));
		}
		return;
	}
	for (int k = 0; k < 4; k++) {
		int x1, y1;
		x1 = x + ___(3)___;
		y1 = y + ___(4)___;
		if (check(x1, y1)) {
			___(5)___;
			___(6)___;
			dfs(x1, y1);
			___(7)___;
			v[x1][y1] = 0;
		}
	}
}

int main() {
cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++)
			cin >> a[i][j];
	}
	dfs(0, 0);
	int d = v1[n - 1][n - 1];
	int x = n - 1, y = n - 1;
	int k;
	int qn[400][2];
	qn[0][0] = n - 1;
	qn[0][1] = n - 1;
	for (k = 1;; k++) {
		x = x - f[d][0];
		y = y - f[d][1];
		qn[k][0] = x;
		qn[k][1] = y;
		d = v1[x][y];
		if (x == 0 && y == 0) break;
	}
	for (int i = k; i >= 0; i--)
		cout << ___(8)___ << ", " << ___(9)___ << endl;
	return 0;
}