[IndexedTree] baekjoon-1275

Author: Seogeurim

README.md

@@ -93,6 +93,7 @@
 | 02  | ⭐️ | [Baekjoon-2042 구간 합 구하기](./src/IndexedTree/P2042)             |      |
 | 03  | ⭐️ | [Baekjoon-2243 사탕상자](./src/IndexedTree/P2243)                  |      |
 | 04  |     | [Baekjoon-5676 음주 코딩](./src/IndexedTree/P5676)               |      |
+| 05  |     | [Baekjoon-1275 커피숍2](./src/IndexedTree/P1275)               |      |
 
 ### Trie
 

src/IndexedTree/P1275/Main.java

@@ -0,0 +1,80 @@
+package IndexedTree.P1275;
+
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int N, Q;
+    static int[] nums;
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/IndexedTree/P1275/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = stoi(st.nextToken());
+        Q = stoi(st.nextToken());
+
+        nums = new int[N];
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) nums[i] = stoi(st.nextToken());
+
+        SegmentTree tree = new SegmentTree(N, nums);
+
+        while (Q-- > 0) {
+            st = new StringTokenizer(br.readLine());
+            int x = stoi(st.nextToken()), y = stoi(st.nextToken());
+            int a = stoi(st.nextToken()), b = stoi(st.nextToken());
+            System.out.println(tree.sum(1, 1, N, x, y));
+            tree.update(1, 1, N, a, b);
+        }
+    }
+
+    private static int stoi(String s) { return Integer.parseInt(s); }
+}
+
+class SegmentTree {
+    long[] tree;
+    int[] arr;
+
+    public SegmentTree(int N, int[] arr) {
+        tree = new long[(int) Math.pow(2, Math.ceil(Math.log(N) / Math.log(2)) + 1)];
+        this.arr = arr;
+        makeTree(1, 1, N);
+    }
+
+    private void makeTree(int idx, int start, int end) {
+        if (start == end) {
+            tree[idx] = arr[start-1];
+            return;
+        }
+        int mid = (start + end) / 2;
+        makeTree(idx*2, start, mid);
+        makeTree(idx*2+1, mid+1, end);
+        tree[idx] = tree[idx*2] + tree[idx*2+1];
+    }
+
+    public long sum(int idx, int start, int end, int x, int y) {
+        if (x > y) {
+            return sum(idx, start, end, y, x);
+        } else {
+            if (end < x || start > y) return 0;
+            if (x <= start && end <= y) return tree[idx];
+            int mid = (start + end) / 2;
+            return sum(idx*2, start, mid, x, y) + sum(idx*2+1, mid+1, end, x, y);
+        }
+    }
+
+    public void update(int idx, int start, int end, int a, int b) {
+        if (end < a || start > a) return;
+        if (start == end) {
+            tree[idx] = b;
+            return;
+        }
+        int mid = (start + end) / 2;
+        update(idx*2, start, mid, a, b);
+        update(idx*2+1, mid+1, end, a, b);
+        tree[idx] = tree[idx*2] + tree[idx*2+1];
+    }
+}

src/IndexedTree/P1275/README.md

@@ -0,0 +1,3 @@
+## [baekjoon-1275] 커피숍2
+
+![image](https://user-images.githubusercontent.com/22045163/104669124-c4f4a400-571c-11eb-819c-09ec291c56fb.png)

src/IndexedTree/P1275/input.txt

@@ -0,0 +1,5 @@
+5 3
+1 2 3 4 5
+2 3 3 1
+3 5 4 1
+5 1 2 3