[백준][Java] 2015번 수들의 합 4 (누적합)

[백준][Java] 2015번 수들의 합 4 (누적합)

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import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.util.HashMap; import java.util.Map; public class Main { private static BufferedReader br = new BufferedReader( new InputStreamReader( System . in )); private static BufferedWriter bw = new BufferedWriter( new OutputStreamWriter( System . out )); public static void main( String [] args) throws IOException{ String [] str = br.readLine(). split ( " " ); int N = stoi(str[ 0 ]); int K = stoi(str[ 1 ]); int [] preSum = new int [N + 1 ]; str = br.readLine(). split ( " " ); for ( int i = 1 ; i < = N; i + + ) { preSum[i] = preSum[i - 1 ] + stoi(str[i - 1 ]); } Map < Integer, Integer > map = new HashMap < > (); long res = 0 ; int count = 0 ; for ( int i = 1 ; i < = N; i + + ) { if (preSum[i] = = K) res + + ; count = map.getOrDefault(preSum[i] - K, 0 ); res + = ( long )count; map.put(preSum[i], map.getOrDefault(preSum[i], 0 ) + 1 ); } System . out . println (res); } private static int stoi( String input) { return Integer. parseInt (input); } } Colored by Color Scripter

from http://aig2029.tistory.com/289 by ccl(A) rewrite - 2021-09-19 18:27:37