diff --git a/bishoe01/DP/Count Square Submatrices with All Ones.swift b/bishoe01/DP/Count Square Submatrices with All Ones.swift
new file mode 100644
index 0000000..dad108a
--- /dev/null
+++ b/bishoe01/DP/Count Square Submatrices with All Ones.swift	
@@ -0,0 +1,45 @@
+class Solution {
+    func countSquares(_ matrix: [[Int]]) -> Int {
+        var answer = 0
+        let maxLen = min(matrix.count, matrix[0].count) // 정사각형 한변 최대길이
+        let WIDTH = matrix[0].count
+        let HEIGHT = matrix.count
+
+        for col in 0 ..< HEIGHT { // 열
+            var point: (x: Int, y: Int)
+            // 큰 박스가 작은 박스를 포함하는 관계
+            // 우측,&아래로갈수록 가능한 변의 길이가 짧아짐
+            for row in 0 ..< WIDTH { // 행
+                point = (x: row, y: col)
+                Pass: for length in stride(from: maxLen, through: 0, by: -1) { // 변 길이로 해주기
+                    if point.y + length > HEIGHT || point.x + length > WIDTH {
+//                        print("point : \(point), length : \(length) , Width : \(WIDTH), Height : \(HEIGHT)")
+                        continue
+                    } // 이게 탐색이 초과해버리면 안되니까 (ex 가로길이가 4인데, 0~3는 되지만 3~6은안되니까 )
+
+                    // 정사각형 돌고 이거 다 1인지 판단하는 함수
+                    var isSquare = true
+                    SquareFunc: for i in point.y ..< point.y + length {
+                        for j in point.x ..< point.x + length {
+                            if matrix[i][j] == 0 {
+                                isSquare = false
+                                break SquareFunc
+                            }
+                        }
+                    }
+                    if isSquare {
+//                        print("point : \(point), length : \(length)")
+                        answer += length
+                        break Pass
+                    }
+                }
+            }
+        }
+
+        return answer
+    }
+}
+
+func 등차수열합(_ n: Int) -> Int {
+    return (n * (2 + (n - 1))) / 2
+}
diff --git a/bishoe01/README.md b/bishoe01/README.md
index 1512a7f..6f4f1ca 100644
--- a/bishoe01/README.md
+++ b/bishoe01/README.md
@@ -3,4 +3,5 @@
 | 차시 |    날짜    | 문제유형 | 링크 | 풀이 |
 |:----:|:---------:|:----:|:-----:|:----:|
 | 1차시 | 2025.03.27 |  구현  | [[3차] 파일명 정렬](https://school.programmers.co.kr/learn/courses/30/lessons/17686)|https://github.com/AlgoLeadMe/AlgoLeadMe-14/pull/1|
+| 1차시 | 2025.04.09 |  DP  | [1277. Count Square Submatrices with All Ones](https://leetcode.com/problems/count-square-submatrices-with-all-ones/description/?envType=problem-list-v2&envId=dynamic-programming)|https://github.com/AlgoLeadMe/AlgoLeadMe-14/pull/11|
 ---