[1600] CF377A DFS 联通

main/300-399/377A.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"bufio"
+	. "fmt"
+	"io"
+)
+
+// https://space.bilibili.com/206214
+func CF377A(_r io.Reader, _w io.Writer) {
+	in := bufio.NewReader(_r)
+	out := bufio.NewWriter(_w)
+	defer out.Flush()
+	dir4 := []struct{ x, y int }{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
+
+	var n, m, k int
+	Fscan(in, &n, &m, &k)
+	a := make([][]byte, n)
+	for i := range a {
+		Fscan(in, &a[i])
+	}
+	vis := make([][]bool, n)
+	for i := range vis {
+		vis[i] = make([]bool, m)
+	}
+	var dfs func(int, int)
+	dfs = func(i, j int) {
+		vis[i][j] = true
+		for _, d := range dir4 {
+			if x, y := i+d.x, j+d.y; 0 <= x && x < n && 0 <= y && y < m && !vis[x][y] && a[x][y] == '.' {
+				dfs(x, y)
+			}
+		}
+		if k > 0 {
+			k--
+			a[i][j] = 'X'
+		}
+	}
+	for i, row := range a {
+		for j, v := range row {
+			if v == '.' {
+				dfs(i, j)
+				for _, r := range a {
+					Fprintf(out, "%s\n", r)
+				}
+				return
+			}
+		}
+	}
+}
+
+//func main() { CF377A(os.Stdin, os.Stdout) }

main/300-399/377A_test.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"github.com/EndlessCheng/codeforces-go/main/testutil"
+	"testing"
+)
+
+// https://codeforces.com/problemset/problem/377/A
+// https://codeforces.com/problemset/status/377/problem/A
+func TestCF377A(t *testing.T) {
+	// just copy from website
+	rawText := `
+inputCopy
+3 4 2
+#..#
+..#.
+#...
+outputCopy
+#.X#
+X.#.
+#...
+inputCopy
+5 4 5
+#...
+#.#.
+.#..
+...#
+.#.#
+outputCopy
+#XXX
+#X#.
+X#..
+...#
+.#.#`
+	testutil.AssertEqualCase(t, rawText, 0, CF377A)
+}