题面见链接：https://www.cnblogs.com/hyf200803050946/p/14882604.html

#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
struct node{
    int x,y;
}t1,t2;
int r,c,ans;
char a[55][55];
int sx,sy,tx,ty;    
bool flag1[55][55],flag2[55][55];
bool L[55][55][55][55]; //L[x][y][i][j]表示从(x,y)到(i,j)的状态 
queue<node>q;
int dir[4][2]={{1,0},{-1,0},{0,-1},{0,1}};
bool check(int x,int y){return x>=1&&x<=r&&y>=1&&y<=c&&a[x][y]!='#';}
int main(){
    scanf("%d %d",&r,&c);
	for(int i=1;i<=r;i++){
		for(int j=1;j<=c;j++){
			scanf("\n%c",&a[i][j]);
			if(a[i][j]=='S')sx=i,sy=j;
			if(a[i][j]=='T')tx=i,ty=j;
		}
	}
    t1.x=sx,t1.y=sy;
    q.push(t1);
    flag1[t1.x][t1.y]=true;
    while(!q.empty()){
        t1=q.front();
        q.pop();
        int I=0,J=0;
        if(a[t1.x][t1.y]=='+'||a[t1.x][t1.y]=='S'||a[t1.x][t1.y]=='T')I=0,J=3;
        if(a[t1.x][t1.y]=='-')I=2,J=3;
        if(a[t1.x][t1.y]=='|')I=0,J=1;
        if(a[t1.x][t1.y]=='#')continue;
        for(int i=I;i<=J;i++){
            t2.x=t1.x+dir[i][0],t2.y=t1.y+dir[i][1];
            if(check(t2.x,t2.y)){
                L[t1.x][t1.y][t2.x][t2.y]=true;
                if(!flag1[t2.x][t2.y]){
                    flag1[t2.x][t2.y]=true;
                	q.push(t2);
                }
            }
        }
    }
    if(!flag1[tx][ty]){
        printf("I'm stuck!");
        return 0; 
    }
    while(!q.empty())q.pop();
    t1.x=tx,t1.y=ty;
    flag2[t1.x][t1.y]=true;
    q.push(t1);
    while(!q.empty()){
        t1=q.front();
        q.pop();
        for(int i=0;i<=3;i++){
            t2.x=t1.x+dir[i][0],t2.y=t1.y+dir[i][1];
            if(check(t2.x,t2.y)&&L[t2.x][t2.y][t1.x][t1.y]&&!flag2[t2.x][t2.y]){
                flag2[t2.x][t2.y]=true;
                q.push(t2);
            }
        }
    }
    for(int i=1;i<=r;i++){
        for(int j=1;j<=c;j++){
        	if(flag1[i][j]&&!flag2[i][j])ans++;
        }
    }
    printf("%d",ans);
    return 0;
} 

格式化后……

#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
struct node {
    int x, y;
} t1, t2;
int r, c, ans;
char a[55][55];
int sx, sy, tx, ty;
bool flag1[55][55], flag2[55][55];
bool L[55][55][55][55];  // L[x][y][i][j]表示从(x,y)到(i,j)的状态
queue<node> q;
int dir[4][2] = { { 1, 0 }, { -1, 0 }, { 0, -1 }, { 0, 1 } };
bool check(int x, int y) { return x >= 1 && x <= r && y >= 1 && y <= c && a[x][y] != '#'; }
int main() {
    scanf("%d %d", &r, &c);
    for (int i = 1; i <= r; i++) {
        for (int j = 1; j <= c; j++) {
            scanf("\n%c", &a[i][j]);
            if (a[i][j] == 'S')
                sx = i, sy = j;
            if (a[i][j] == 'T')
                tx = i, ty = j;
        }
    }
    t1.x = sx, t1.y = sy;
    q.push(t1);
    flag1[t1.x][t1.y] = true;
    while (!q.empty()) {
        t1 = q.front();
        q.pop();
        int I = 0, J = 0;
        if (a[t1.x][t1.y] == '+' || a[t1.x][t1.y] == 'S' || a[t1.x][t1.y] == 'T')
            I = 0, J = 3;
        if (a[t1.x][t1.y] == '-')
            I = 2, J = 3;
        if (a[t1.x][t1.y] == '|')
            I = 0, J = 1;
        if (a[t1.x][t1.y] == '#')
            continue;
        for (int i = I; i <= J; i++) {
            t2.x = t1.x + dir[i][0], t2.y = t1.y + dir[i][1];
            if (check(t2.x, t2.y)) {
                L[t1.x][t1.y][t2.x][t2.y] = true;
                if (!flag1[t2.x][t2.y]) {
                    flag1[t2.x][t2.y] = true;
                    q.push(t2);
                }
            }
        }
    }
    if (!flag1[tx][ty]) {
        printf("I'm stuck!");
        return 0;
    }
    while (!q.empty()) q.pop();
    t1.x = tx, t1.y = ty;
    flag2[t1.x][t1.y] = true;
    q.push(t1);
    while (!q.empty()) {
        t1 = q.front();
        q.pop();
        for (int i = 0; i <= 3; i++) {
            t2.x = t1.x + dir[i][0], t2.y = t1.y + dir[i][1];
            if (check(t2.x, t2.y) && L[t2.x][t2.y][t1.x][t1.y] && !flag2[t2.x][t2.y]) {
                flag2[t2.x][t2.y] = true;
                q.push(t2);
            }
        }
    }
    for (int i = 1; i <= r; i++) {
        for (int j = 1; j <= c; j++) {
            if (flag1[i][j] && !flag2[i][j])
                ans++;
        }
    }
    printf("%d", ans);
    return 0;
}