B_6588

Algorithm_Baek/Basic/B_300/B_6588_골드바흐의추측.java

@@ -0,0 +1,89 @@
+package B_300_수학1;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class B_6588_골드바흐의추측 {
+
+ static int a = 3;
+ static int b = 0;
+ static int x;
+ static StringBuilder sb;
+ public static void main(String[] args) throws NumberFormatException, IOException {
+
+ BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+ sb = new StringBuilder();
+
+ /* 에라토네스의 체 */
+ /*
+ boolean[] chae = new boolean[1000001];
+ for(int i=2; i<=1000000; i++) {
+ if(!chae[i]) {
+ for(int j=i*2; j<=1000000; j+=i) {
+ chae[j]=true;
+ }
+ }
+ }
+ for(int i=1; i<=1000000; i++) {
+ if(!chae[i]) {
+ System.out.println(i);
+ }
+ }
+ */
+
+
+ while(true) {
+ a = 3;
+ x = Integer.parseInt(br.readLine());
+ if(x==0) break;
+ b = getB(a);
+ checkB(a,b);
+ }
+
+ System.out.println(sb);
+ }
+
+ static void getA(int nowA) {
+// if(a>x) return;
+ int idx = 2;
+ boolean check = true;
+ while(idx<=Math.sqrt(nowA)){
+ if(nowA%idx==0) {
+ check = false;
+ break;
+ }
+ idx++;
+ }
+ if(check) a = nowA;
+ else getA(nowA+1);
+ }
+
+ static int getB(int nowA) {
+ return x-nowA;
+ }
+
+ static void checkB(int nowA, int nowB) {
+
+ int idx = 2;
+ boolean check = true;
+ while(idx<=Math.sqrt(nowB)){
+ if(nowB%idx==0) {
+ check = false;
+ break;
+ }
+ idx++;
+ }
+
+ if(check) sb.append(x+" = "+nowA+" + "+nowB+"\n");
+ else {
+ getA(nowA+1);
+// if(a<x) {
+ checkB(a,getB(a));
+// }else {
+// sb.append("Goldbach's conjecture is wrong.\n");
+// }
+
+ }
+ }
+}