Merge pull request #1114 from AlgorithmWithGod/0224LJH

[20251014] BOJ / P2 / 수 지우기 / 이종환

Author: ShinHeeEul

0224LJH/202510/14 BOJ 수 지우기.md

@@ -0,0 +1,103 @@
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Main {
+	
+	static int len;
+	static int[] arr,numCnt,eraseCnt;
+	static String ans;
+    
+    public static void main(String[] args) throws IOException {
+    	init();
+    	process();
+    	print();
+    }
+    private static void init() throws IOException{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        
+        String input = br.readLine();
+        len = input.length();
+        arr = new int[len];
+        
+        numCnt = new int[10];
+        for (int i = 0; i < len; i++) {
+            arr[i] = input.charAt(i) - '0';
+            numCnt[arr[i]]++;
+        }
+        
+        String erase = br.readLine();
+        eraseCnt = new int[10];
+        for (int i = 0; i < erase.length(); i++) {
+            eraseCnt[erase.charAt(i) - '0']++;
+        }
+    }
+    
+    private static void process() {        
+        // 남을 숫자 개수
+        int[] remaining = new int[10];
+        int totalRemain = 0;
+        for (int i = 0; i < 10; i++) {
+            remaining[i] = numCnt[i] - eraseCnt[i];
+            totalRemain += remaining[i];
+        }
+        
+        // suffix count 전처리
+        int[][] suffixCnt = new int[len + 1][10];
+        for (int i = len - 1; i >= 0; i--) {
+            for (int d = 0; d < 10; d++) {
+                suffixCnt[i][d] = suffixCnt[i + 1][d];
+            }
+            suffixCnt[i][arr[i]]++;
+        }
+        
+        StringBuilder sb = new StringBuilder();
+        int pos = 0;
+        
+        // 결과 길이만큼 반복
+        for (int resultPos = 0; resultPos < totalRemain; resultPos++) {
+            // 가장 큰 숫자부터 시도
+            for (int num = 9; num >= 0; num--) {
+                if (remaining[num] == 0) continue;
+                
+                // 원본에서 num을 찾기
+                boolean found = false;
+                for (int i = pos; i < len; i++) {
+                    if (arr[i] == num) {
+                        // 이 num을 선택했을 때, i+1부터 나머지를 만들 수 있는지 확인
+                        remaining[num]--;
+                        
+                        boolean canMake = true;
+                        for (int d = 0; d < 10; d++) {
+                            if (suffixCnt[i + 1][d] < remaining[d]) {
+                                canMake = false;
+                                break;
+                            }
+                        }
+                        
+                        if (canMake) {
+                            sb.append(num);
+                            pos = i + 1;
+                            found = true;
+                            break;
+                        } else {
+                            remaining[num]++;
+                        }
+                    }
+                }
+                
+                if (found) break;
+            }
+        }
+        
+        ans = sb.toString();
+    }
+    
+
+    
+    private static void print() {
+        System.out.println(ans);
+    }
+}
+```