diff --git a/111/step1.cpp b/111/step1.cpp
new file mode 100644
index 0000000..de9619f
--- /dev/null
+++ b/111/step1.cpp
@@ -0,0 +1,28 @@
+/*
+Solve Time : 07:17
+
+Time : O(V + E)
+Space : O(V)
+
+root ~ leafまでの距離、という部分を読み違えて時間を多少ロスしたものの、特につまるところなく解けた。
+*/
+class Solution {
+public:
+  int minDepth(TreeNode* root) {
+    queue<pair<TreeNode*, int>> nodes_and_depths;
+    nodes_and_depths.emplace(root, 1);
+    while (!nodes_and_depths.empty()) {
+      auto [node, depth] = nodes_and_depths.front();
+      nodes_and_depths.pop();
+      if (!node) {
+        continue;
+      }
+      if (node->left == nullptr && node->right == nullptr) {
+        return depth;
+      }
+      nodes_and_depths.emplace(node->left, depth + 1);
+      nodes_and_depths.emplace(node->right, depth + 1);      
+    }
+    return 0;
+  }
+};
diff --git a/111/step2.cpp b/111/step2.cpp
new file mode 100644
index 0000000..beb9559
--- /dev/null
+++ b/111/step2.cpp
@@ -0,0 +1,26 @@
+/*
+Time : O(V + E)
+Space : O(V)
+
+再帰,DFSで解いてみる。
+rootの処理をどうしても分岐で処理できなかったので最初のrootの面倒を見る関数と再帰処理をする関数とに分けた。
+*/
+class Solution {
+public:
+  int minDepth(TreeNode* root) {
+    if (!root) {
+      return 0;
+    }
+    return minDepthRecursive(root);
+  }
+ private:
+  int minDepthRecursive(TreeNode* root) {
+    if (!root) {
+      return numeric_limits<int>::max();
+    }
+    if (root->left == nullptr && root->right == nullptr) {
+      return 1;
+    }
+    return min(minDepthRecursive(root->left), minDepthRecursive(root->right)) + 1;
+  }
+};
diff --git a/111/step3.cpp b/111/step3.cpp
new file mode 100644
index 0000000..08e242a
--- /dev/null
+++ b/111/step3.cpp
@@ -0,0 +1,20 @@
+class Solution {
+public:
+  int minDepth(TreeNode* root) {
+    queue<pair<TreeNode*, int>> nodes_and_depths;
+    nodes_and_depths.emplace(root, 1);
+    while (!nodes_and_depths.empty()) {
+      auto [node, depth] = nodes_and_depths.front();
+      nodes_and_depths.pop();
+      if (!node) {
+        continue;
+      }
+      if (!(node->left || node->right)) {
+        return depth;
+      }
+      nodes_and_depths.emplace(node->left, depth + 1);
+      nodes_and_depths.emplace(node->right, depth + 1);
+    }
+    return 0;
+  }
+};