Merge pull request #820 from AlgorithmWithGod/JHLEE325

[20250905] BOJ / G1 / 구간 곱 구하기 / 이준희

Author: ShinHeeEul

JHLEE325/202509/05 BOJ G1 구간 곱 구하기.md

@@ -0,0 +1,77 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        StringBuilder sb = new StringBuilder();
+
+        int n = Integer.parseInt(st.nextToken());
+        int m = Integer.parseInt(st.nextToken());
+        int k = Integer.parseInt(st.nextToken());
+
+        long[] arr = new long[n];
+        long[] tree = new long[4 * n];
+
+        for (int i = 0; i < n; i++) {
+            arr[i] = Integer.parseInt(br.readLine());
+        }
+
+        init(arr, tree, 1, 0, n - 1);
+
+        for (int i = 0; i < m + k; i++) {
+            st = new StringTokenizer(br.readLine());
+            int op = Integer.parseInt(st.nextToken());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            if (op == 2) {
+                sb.append(query(tree, 1, 0, n - 1, a - 1, b - 1) + "\n");
+            } else {
+                update(arr, tree, 1, 0, n - 1, a - 1, b);
+            }
+        }
+
+        System.out.println(sb.toString());
+    }
+
+    static void init(long[] arr, long[] tree, int node, int start, int end) {
+        if (start == end) {
+            tree[node] = arr[start];
+        } else {
+            init(arr, tree, node * 2, start, (start + end) / 2);
+            init(arr, tree, node * 2 + 1, (start + end) / 2 + 1, end);
+            tree[node] = tree[node * 2] * tree[node * 2 + 1] % 1000000007;
+        }
+    }
+
+    static void update(long[] arr, long[] tree, int node, int start, int end, int index, long val) {
+        if (index < start || index > end) {
+            return;
+        }
+        if (start == end) {
+            arr[index] = val;
+            tree[node] = val;
+            return;
+        }
+        update(arr, tree, node * 2, start, (start + end) / 2, index, val);
+        update(arr, tree, node * 2 + 1, (start + end) / 2 + 1, end, index, val);
+        tree[node] = tree[node * 2] * tree[node * 2 + 1] % 1000000007;
+    }
+
+    static long query(long[] tree, int node, int start, int end, int left, int right) {
+        if (left > end || right < start) {
+            return 1;
+        }
+        if (left <= start && end <= right) {
+            return tree[node];
+        }
+        long lmul = query(tree, node * 2, start, (start + end) / 2, left, right);
+        long rmul = query(tree, node * 2 + 1, (start + end) / 2 + 1, end, left, right);
+        return lmul * rmul % 1000000007;
+    }
+}
+```