[20250819] BOJ / G2 / 로봇 조종하기 / 이종환

Author: 0224LJH

0224LJH/202508/19 BOJ 로봇 조종하기 .md

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+```java
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class Main {
+
+    static int height,width,ans;
+
+    static int[][] arr;
+    static int[][][] dp;
+
+    static final int TOP = 0;
+    static final int LEFT = 1;
+    static final int RIGHT = 2;
+    static final int MIN = Integer.MIN_VALUE/2;
+
+    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));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        height = Integer.parseInt(st.nextToken());
+        width = Integer.parseInt(st.nextToken());
+        arr = new int[height][width];
+        dp = new int[height][width][3];
+        ans = MIN;
+        // 합의 최댓값을 직전에 어느 방향에서 왔는지에 따라 구분.
+        // 0 ,1 , 2가 순서대로 위,왼,오
+
+        for (int i = 0; i < height; i++){
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < width; j++){
+                arr[i][j] = Integer.parseInt(st.nextToken());
+                Arrays.fill(dp[i][j], MIN);
+            }
+        }
+
+    }
+
+    private static void process() throws IOException {
+        calculateFirstLine();
+        for (int i = 1; i < height; i++){
+            calculateFromTop(i);
+            calculateFromLeft(i);
+            calculateFromRight(i);
+        }
+
+        for (int i = 0; i < 3; i++){
+            ans = Math.max (ans,dp[height-1][width-1][i]);
+        }
+
+    }
+
+    private static void calculateFromRight(int curHeight) {
+        dp[curHeight][width-1][RIGHT] = dp[curHeight][width-1][TOP];
+        for (int i = width - 2; i >= 0; i--) {
+            dp[curHeight][i][RIGHT] = arr[curHeight][i] + Math.max(dp[curHeight][i+1][TOP], dp[curHeight][i+1][RIGHT]);
+        }
+    }
+
+    private static void calculateFromLeft(int curHeight) {
+        dp[curHeight][0][LEFT] = dp[curHeight][0][TOP];
+        for (int i = 1; i < width; i++){
+            dp[curHeight][i][LEFT] = arr[curHeight][i] + Math.max(dp[curHeight][i-1][TOP],  dp[curHeight][i-1][LEFT]) ;
+        }
+    }
+
+    private static void calculateFromTop(int curHeight) {
+        for (int i = 0; i < width; i++){
+            int curLargest = MIN;
+            for (int j = 0; j < 3; j++) curLargest = Math.max(curLargest, dp[curHeight-1][i][j]);
+
+            dp[curHeight][i][TOP] = curLargest + arr[curHeight][i];
+        }
+    }
+
+    private static void calculateFirstLine() {
+        int cur = 0;
+        for (int i = 0; i < width; i++){
+            cur += arr[0][i];
+            dp[0][i][0] = cur;
+        }
+    }
+
+
+    private static void print() {
+        System.out.println(ans);
+    }
+}
+```