[20251117] BOJ / G4 / 서울에서 경산까지 / 이강현

lkhyun/202511/17 BOJ G4 서울에서 경산까지.md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    static StringTokenizer st;
+    static int N, K;
+    static int[] vehicleTime, vehiclePrice, walkTime, walkPrice;
+    static int[] dp;
+    static boolean[] impossible;
+
+    public static void main(String[] args) throws Exception {
+        st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        K = Integer.parseInt(st.nextToken());
+
+        walkTime = new int[N + 1];
+        walkPrice = new int[N + 1];
+        vehicleTime = new int[N + 1];
+        vehiclePrice = new int[N + 1];
+        dp = new int[K + 1];
+        impossible = new boolean[K + 1];
+
+        for (int i = 1; i <= N; i++) {
+            st = new StringTokenizer(br.readLine());
+            walkTime[i] = Integer.parseInt(st.nextToken());
+            walkPrice[i] = Integer.parseInt(st.nextToken());
+            vehicleTime[i] = Integer.parseInt(st.nextToken());
+            vehiclePrice[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.fill(impossible, true);
+
+        if (walkTime[1] <= K) {
+            dp[walkTime[1]] = walkPrice[1];
+            impossible[walkTime[1]] = false;
+        }
+        if (vehicleTime[1] <= K) {
+            if (impossible[vehicleTime[1]]) {
+                dp[vehicleTime[1]] = vehiclePrice[1];
+                impossible[vehicleTime[1]] = false;
+            } else {
+                dp[vehicleTime[1]] = Math.max(dp[vehicleTime[1]], vehiclePrice[1]);
+            }
+        }
+
+        for (int i = 2; i <= N; i++) {
+            boolean[] nextImpossible = new boolean[K + 1];
+            Arrays.fill(nextImpossible, true);
+            int[] nextDp = new int[K + 1];
+
+            for (int j = K; j >= 0; j--) {
+                if (impossible[j]) continue;
+
+                if (j + walkTime[i] <= K) {
+                    int nextTime = j + walkTime[i];
+                    int nextMoney = dp[j] + walkPrice[i];
+
+                    if (nextImpossible[nextTime]) {
+                        nextDp[nextTime] = nextMoney;
+                        nextImpossible[nextTime] = false;
+                    } else {
+                        nextDp[nextTime] = Math.max(nextDp[nextTime], nextMoney);
+                    }
+                }
+
+                if (j + vehicleTime[i] <= K) {
+                    int nextTime = j + vehicleTime[i];
+                    int nextMoney = dp[j] + vehiclePrice[i];
+
+                    if (nextImpossible[nextTime]) {
+                        nextDp[nextTime] = nextMoney;
+                        nextImpossible[nextTime] = false;
+                    } else {
+                        nextDp[nextTime] = Math.max(nextDp[nextTime], nextMoney);
+                    }
+                }
+            }
+
+            dp = nextDp;
+            impossible = nextImpossible;
+        }
+
+        int answer = 0;
+        for (int j = 0; j <= K; j++) {
+            if (!impossible[j]) {
+                answer = Math.max(answer, dp[j]);
+            }
+        }
+
+        bw.write(answer + "");
+        bw.close();
+    }
+}
+```