BFS--宽搜求最短路径

10 10
#S######.#
......#..#
.#.##.##.#
.#........
##.##.####
....#....#
.#######.#
....#.....
.####.###.
....#...G#

#是障碍，.是通道，S是起点，G是终点

求出最短路径长度和路径

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<queue>
#include<cstdio>

using namespace std;

typedef pair<int, int> P;

const int MAX_N = 105;
const int MAX_M = 105;

char field[MAX_N][MAX_M];
bool Visited[MAX_N][MAX_M];
int PathLength[MAX_N][MAX_M];
P Pre[MAX_N][MAX_M];

int N, M;
int sx, sy;
int dx, dy;

int Dir[4][2] = { 1,0,-1,0,0,1,0,-1 };

int bfs()
{
  memset(Visited, false, sizeof(Visited));
  memset(PathLength, 0, sizeof(PathLength));
  queue<P> q;
  q.push(P(sx, sy));
  Visited[sx][sy] = true;
  while (!q.empty()) {
    P p = q.front(); q.pop();
    if (p.first == dx && p.second == dy) {
      break;
    }
    for (int i = 0; i < 4; i++) {
      int nx = p.first + Dir[i][0];
      int ny = p.second + Dir[i][1];
      if (nx >= 0 && nx < N && ny >= 0 && ny < M && !Visited[nx][ny] && field[nx][ny] != '#') {
        q.push(P(nx, ny));
        Visited[nx][ny] = true;
        PathLength[nx][ny] = PathLength[p.first][p.second] + 1;
        Pre[nx][ny] = P(p.first, p.second);
      }
    }
  }
  return PathLength[dx][dy];
}

void Print(P Cur) {
  if (Cur.first == sx && Cur.second == sy) {
    cout << "(" << sx << "," << sy << ")" << endl;
    return;
  }
  Print(Pre[Cur.first][Cur.second]);
  cout << "(" << Cur.first << "," << Cur.second << ")" << endl;
}

int main() {
  scanf("%d%d", &N, &M);
  for (int i = 0; i < N; i++) {
    scanf("%s", &field[i]);
    for (int j = 0; j < M; j++) {
      if (field[i][j] == 'S') {
        sx = i;sy = j;
      }
      if (field[i][j] == 'G') {
        dx = i; dy = j;
      }
    }
  }
  int Result = bfs();
  printf("%d\n", Result);
  Print(P(dx,dy));
  system("pause");
  return 0;
}