solved with two pointer

Author: DeveloperYard

baekjoon/boj1940.java

@@ -0,0 +1,56 @@
+package Algo;
+ 
+import java.util.*;
+import java.io.*;
+
+class Jumong {
+	static int start_idx = 0;
+	static int end_idx = 0;
+	static int count = 0;
+	static int[] optionArr;
+	
+	static int printCount(int comp) {
+//		System.out.println(Arrays.toString(optionArr));
+		while (start_idx < end_idx) {
+			if(comp > optionArr[start_idx] + optionArr[end_idx]) {
+				start_idx++;
+			} else if (comp < optionArr[start_idx] + optionArr[end_idx]) {
+				end_idx--;
+			} else {
+//				System.out.println("start_idx : " + start_idx + " end_idx : " + end_idx);
+				count++;
+				start_idx++;
+				end_idx--;
+			}	
+		}
+		return count;
+	}
+}
+
+public class boj1940{
+	public static void main(String[] args) throws IOException{
+		
+		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		 StringTokenizer st = new StringTokenizer(br.readLine());
+		 
+		 int N = Integer.valueOf(st.nextToken());
+		 
+		 
+		 st = new StringTokenizer(br.readLine());
+		 int m = Integer.valueOf(st.nextToken());
+		 
+		 st = new StringTokenizer(br.readLine());
+		 int[] intArr = new int[N];
+		 
+		 for(int i = 0; i<N; i++) {
+			 intArr[i] = Integer.parseInt(st.nextToken());
+		 }
+		 Jumong.optionArr = intArr;
+		 Jumong.end_idx = N-1;
+		 Arrays.sort(Jumong.optionArr);
+		 
+		 System.out.println(Jumong.printCount(m));
+		 
+		 
+	}
+}