diff --git a/0322-coin-change/memo.md b/0322-coin-change/memo.md
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+++ b/0322-coin-change/memo.md
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+### step1
+
+DFSでコイン1枚ずつ遷移させていく方法しか思いつかず、TLEしてしまったのでChatGPTにDPで解き直してもらった。
+他の方のPRを見ていると、配るDP, もらうDPに関していくつか記述があったので調べてみた。（https://algo-method.com/descriptions/78）
+今回書いたDPは配るDPらしい。
+
+### step2
+
+変更点なし。
+
+### step3
+
+3回通すまで書き直し。
diff --git a/0322-coin-change/step1.cpp b/0322-coin-change/step1.cpp
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+++ b/0322-coin-change/step1.cpp
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+class Solution {
+public:
+    int coinChange(vector<int>& coins, int amount) {
+        const int INF = 1e9;
+
+        vector<int> min_coins(amount + 1, INF);
+        min_coins[0] = 0;
+
+        for (int i = 0; i <= amount; i++) {
+            for (int coin : coins) {
+                if (i <= amount - coin) {
+                    min_coins[i + coin] = min(min_coins[i + coin], min_coins[i] + 1);
+                }
+            }
+        }
+        return min_coins[amount] == INF ? -1 : min_coins[amount];
+    }
+};
diff --git a/0322-coin-change/step2.cpp b/0322-coin-change/step2.cpp
new file mode 100644
index 0000000..97cff6a
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+++ b/0322-coin-change/step2.cpp
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+class Solution {
+public:
+    int coinChange(vector<int>& coins, int amount) {
+        const int INF = 1e9;
+
+        vector<int> min_coins(amount + 1, INF);
+        min_coins[0] = 0;
+
+        for (int i = 0; i <= amount; i++) {
+            for (int coin : coins) {
+                if (i <= amount - coin) {
+                    min_coins[i + coin] = min(min_coins[i + coin], min_coins[i] + 1);
+                }
+            }
+        }
+        return min_coins[amount] == INF ? -1 : min_coins[amount];
+    }
+};
diff --git a/0322-coin-change/step3.cpp b/0322-coin-change/step3.cpp
new file mode 100644
index 0000000..48c0900
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+++ b/0322-coin-change/step3.cpp
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+class Solution {
+public:
+    int coinChange(vector<int>& coins, int amount) {
+        const int INF = 1e9;
+        vector<int> min_coins(amount + 1, INF);
+        min_coins[0] = 0;
+
+        for (int i = 0; i <= amount; i++) {
+            for (int coin : coins) {
+                if (i <= amount - coin) {
+                    min_coins[i + coin] = min(min_coins[i + coin], min_coins[i] + 1);
+                }
+            }
+        }
+        return min_coins[amount] == INF ? -1 : min_coins[amount];
+    }
+};