[20250826] BOJ / G1 / 최솟값과 최댓값 / 이준희

Author: JHLEE325

JHLEE325/202508/26 BOJ G1 최솟값과 최댓값.md

@@ -0,0 +1,95 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args) throws Exception {
+        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[] arr = new int[n];
+        for(int i=0;i<n;i++){
+            arr[i]= Integer.parseInt(br.readLine());
+        }
+
+        int[] min_tree = new int[4*n];
+        int[] max_tree = new int[4*n];
+
+        init(arr,min_tree,1,0,n-1);
+        initmax(arr,max_tree,1,0,n-1);
+
+        for(int i=0;i<m;i++){
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            int min = query(min_tree,1,0,n-1,a-1,b-1);
+            int max = querymax(max_tree,1,0,n-1,a-1,b-1);
+            sb.append(min+" "+max+"\n");
+        }
+
+        System.out.println(sb.toString());
+    }
+
+    static void init(int[] arr, int[] 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] = Math.min(tree[node * 2], tree[node * 2 + 1]);
+        }
+    }
+
+    static int query(int[] 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];
+        }
+        int lmin = query(tree, node*2, start, (start+end)/2, left, right);
+        int rmin = query(tree, node*2+1, (start+end)/2+1, end, left, right);
+        if (lmin == -1) {
+            return rmin;
+        } else if (rmin == -1) {
+            return lmin;
+        } else {
+            return Math.min(lmin, rmin);
+        }
+    }
+
+    static void initmax(int[] arr, int[] tree, int node, int start, int end) {
+        if (start == end) {
+            tree[node] = arr[start];
+        } else {
+            initmax(arr, tree, node * 2, start, (start + end) / 2);
+            initmax(arr, tree, node * 2 + 1, (start + end) / 2 + 1, end);
+            tree[node] = Math.max(tree[node * 2], tree[node * 2 + 1]);
+        }
+    }
+
+    static int querymax(int[] 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];
+        }
+        int lmax = querymax(tree, node*2, start, (start+end)/2, left, right);
+        int rmax = querymax(tree, node*2+1, (start+end)/2+1, end, left, right);
+        if (lmax == -1) {
+            return rmax;
+        } else if (rmax == -1) {
+            return lmax;
+        } else {
+            return Math.max(lmax, rmax);
+        }
+    }
+}
+
+```