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540C.go
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540C.go
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package main
import (
"bufio"
. "fmt"
"io"
)
// github.com/EndlessCheng/codeforces-go
func CF540C(_r io.Reader, out io.Writer) {
in := bufio.NewReader(_r)
dir4 := []struct{ x, y int }{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
var n, m, sx, sy, tx, ty, c int
Fscan(in, &n, &m)
g := make([][]byte, n)
for i := range g {
Fscan(in, &g[i])
}
Fscan(in, &sx, &sy, &tx, &ty)
sx--
sy--
tx--
ty--
if sx == tx && sy == ty {
for _, d := range dir4 {
if x, y := tx+d.x, ty+d.y; 0 <= x && x < n && 0 <= y && y < m && g[x][y] == '.' {
Fprint(out, "YES")
return
}
}
Fprint(out, "NO")
return
}
g[sx][sy] = '.'
if g[tx][ty] == '.' {
for _, d := range dir4 {
if x, y := tx+d.x, ty+d.y; 0 <= x && x < n && 0 <= y && y < m && g[x][y] == '.' {
c++
}
}
if c < 2 {
Fprint(out, "NO")
return
}
}
vis := make([][]bool, n)
for i := range vis {
vis[i] = make([]bool, m)
}
var f func(int, int) bool
f = func(x, y int) bool {
if x < 0 || x >= n || y < 0 || y >= m || vis[x][y] {
return false
}
if x == tx && y == ty {
return true
}
if g[x][y] == 'X' {
return false
}
vis[x][y] = true
for _, d := range dir4 {
if f(x+d.x, y+d.y) {
return true
}
}
return false
}
if f(sx, sy) {
Fprint(out, "YES")
} else {
Fprint(out, "NO")
}
}
//func main() { CF540C(os.Stdin, os.Stdout) }