이예진: [BOJ] 19939 박 터뜨리기_241122

Author: yeahdy

BOJ/15001-20000번/YJ_19939.java

@@ -0,0 +1,30 @@
+import java.io.*;
+import java.util.*;
+
+//2 <= N <= 10^5
+//누적합
+public class YJ_19939 {
+    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.parseInt(st.nextToken());
+        int K = Integer.parseInt(st.nextToken());
+
+        int[] dp = new int[K+1];
+        for(int i=1; i<K+1; i++){
+            dp[i] = dp[i-1] + i;
+        }
+
+        int minCount = dp[K];
+        if(N < minCount){
+            System.out.println(-1);
+        }else{
+            int result = (N-minCount) % K;
+            if(result == 0){
+                System.out.println(K-1);
+            }else{
+                System.out.println(K);   //K+result - (result*1)
+            }
+        }
+    }
+}