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Author: jskim7018

LC_854.java

@@ -0,0 +1,39 @@
+package leetcode;
+
+import java.util.HashMap;
+
+class LC_854 {
+    public int kSimilarity(String s1, String s2) {
+        HashMap<String,Integer> dp = new HashMap<>();
+        StringBuilder sb1 = new StringBuilder(s1);
+        return solve(0,sb1, s2, dp);
+    }
+
+    public int solve(int idx, StringBuilder s1, String s2, HashMap<String,Integer> dp) {
+        if(idx >= s1.length()) return 0;
+        if(dp.containsKey(s1.toString())) return dp.get(s1.toString());
+        int ret = Integer.MAX_VALUE;
+        if(s1.charAt(idx) == s2.charAt(idx)) {
+            ret = solve(idx+1, s1,s2, dp);
+        } else {
+            for(int i=idx+1;i<s2.length();i++) {
+                if(s2.charAt(idx) == s1.charAt(i) && s2.charAt(i) != s1.charAt(i)) {
+                    swap(idx, i, s1);
+                    int curr = 1+solve(idx+1, s1,s2, dp);
+                    swap(idx, i, s1);
+                    ret = Math.min(ret, curr);
+                }
+            }
+        }
+        if(ret == Integer.MAX_VALUE) ret = 0;
+        dp.put(s1.toString(), ret);
+        return ret;
+    }
+
+    private void swap(int i, int j, StringBuilder sb) {
+        char tmp = sb.charAt(i);
+        sb.replace(i, i+1, sb.charAt(j)+"");
+        sb.replace(j, j+1, tmp+"");
+    }
+
+}