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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;
}

BFS--宽搜求最短路径_i++

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