[IndexedTree] baekjoon-2268

Author: Seogeurim

README.md

@@ -94,6 +94,7 @@
 | 03  | ⭐️ | [Baekjoon-2243 사탕상자](./src/IndexedTree/P2243)                  |      |
 | 04  |     | [Baekjoon-5676 음주 코딩](./src/IndexedTree/P5676)               |      |
 | 05  |     | [Baekjoon-1275 커피숍2](./src/IndexedTree/P1275)               |      |
+| 06  |     | [Baekjoon-2268 수들의 합](./src/IndexedTree/P2268)               |      |
 
 ### Trie
 

src/IndexedTree/P2268/Main.java

@@ -0,0 +1,53 @@
+package IndexedTree.P2268;
+
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    final static char CMD_SUM = '0', CMD_MOD = '1';
+    static int N, M;
+    static long[] segmentTree;
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/IndexedTree/P2268/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        segmentTree = new long[(int) Math.pow(2, Math.ceil(Math.log(N) / Math.log(2)) + 1)];
+
+        StringBuilder sb = new StringBuilder();
+        while (M-- > 0) {
+            st = new StringTokenizer(br.readLine());
+            char cmd = st.nextToken().charAt(0);
+            int p1 = Integer.parseInt(st.nextToken()), p2 = Integer.parseInt(st.nextToken());
+            if (cmd == CMD_SUM) sb.append(sum(1, 1, N, p1, p2)).append("\n");
+            else if (cmd == CMD_MOD) modify(1, 1, N, p1, p2);
+        }
+        System.out.println(sb.toString());
+    }
+
+    static long sum(int idx, int start, int end, int i, int j) {
+        if (i > j) {
+            return sum(idx, start, end, j, i);
+        } else {
+            if (j < start || end < i) return 0;
+            if (i <= start && end <= j) return segmentTree[idx];
+            return sum(idx*2, start, (start+end)/2, i, j)
+                    + sum(idx*2+1, (start+end)/2 + 1, end, i, j);
+        }
+    }
+
+    static void modify(int idx, int start, int end, int i, int k) {
+        if (i < start || end < i) return;
+        if (start == end) segmentTree[idx] = k;
+        else {
+            modify(idx*2, start, (start+end)/2, i, k);
+            modify(idx*2+1, (start+end)/2 + 1, end, i, k);
+            segmentTree[idx] = segmentTree[idx*2] + segmentTree[idx*2+1];
+        }
+    }
+}

src/IndexedTree/P2268/README.md

@@ -0,0 +1,3 @@
+## [baekjoon-2268] 수들의 합
+
+![image](https://user-images.githubusercontent.com/22045163/104674536-27eb3880-5727-11eb-8fbc-b7b6ca110e4a.png)

src/IndexedTree/P2268/input.txt

@@ -0,0 +1,6 @@
+3 5
+0 1 3
+1 1 2
+1 2 3
+0 2 3
+0 1 3