大佬康康我犯了啥

#include<bits/stdc++.h>
using namespace std;
int n,m,tr=1;
int nx[4]= {-1,1,0,0};
int ny[4]= {0,0,-1,1};
struct qq {
	int x;
	int y;//x,y
	int dx;
	int dy;//duiying
	char node;
	int k;//queue k
};
qq dt[305][305],in,out;
queue<qq> q;

int main() {
	char x;
	cin >> n >> m;
	string s;
	qq zm[26];//x,y qian;dx,dy hou;
	for(int i=0; i<26; i++) {
		zm[i].x=0;
		zm[i].y=0;
		zm[i].dx=0;
		zm[i].dy=0;
	}


	for(int i=1; i<=n; i++) {
		cin >> s;
		for(int j=1; j<=m; j++) {
			x=s[j-1];
			//cout << i << j << " " << x << endl;//
			dt[j][i].x=j;
			dt[j][i].y=i;
			dt[j][i].node=x;
			dt[j][i].k=-1;
			if(x-'A'>=0&&'Z'-x>=0) {
				if(zm[x-'A'].x==0) {
					zm[x-'A'].x=j;
					zm[x-'A'].y=i;
				} else {
					zm[x-'A'].dx=j;
					zm[x-'A'].dy=i;
					dt[zm[x-'A'].x][zm[x-'A'].y].dx=j;
					dt[zm[x-'A'].x][zm[x-'A'].y].dy=i;
					dt[j][i].dx=zm[x-'A'].x;
					dt[j][i].dy=zm[x-'A'].y;
				}
			} else if(x=='@') {
				in.x=j;
				in.y=i;
				dt[j][i].k=0;
			}
		}
	}
	//cout << zm['W'-'A'].x << " "<< zm['W'-'A'].y << " " << zm['W'-'A'].dx << " " << zm['W'-'A'].dy;//
	//cout << dt[3][2].dx << dt[3][2].dy;//

//------------------------------------------------------------------------------------a-----------------
	qq now,noww;
	dt[in.x][in.y].k=0;
	now=dt[in.x][in.y];
	q.push(now);
	while(!q.empty()&&tr) {
		now=q.front();
		q.pop();
		if(now.node=='='){
			cout << now.k;
			return 0;
		}

		for(int i=0; i<4; i++) {
			int tx=nx[i]+now.x,ty=ny[i]+now.y;
			if(dt[tx][ty].node>='A'&&dt[tx][ty].node<='Z'&&dt[tx][ty].dx!=0){
				int nx=dt[tx][ty].dx;
				int ny=dt[tx][ty].dy;
				tx=nx;ty=ny;
			}
			if(tx<1||tx>n||ty<1||ty>m||(dt[tx][ty].k!=-1&&(dt[tx][ty].node<'A'||dt[tx][ty].node>'Z'))||dt[tx][ty].node=='#'){
				continue;
			}
			dt[tx][ty].k=now.k+1;
			q.push(dt[tx][ty]);
		}
	}
}