g0501_0600.s0560_subarray_sum_equals_k.Solution Maven / Gradle / Ivy

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package g0501_0600.s0560_subarray_sum_equals_k;

// #Medium #Top_100_Liked_Questions #Array #Hash_Table #Prefix_Sum #Data_Structure_II_Day_5_Array
// #Big_O_Time_O(n)_Space_O(n) #2024_11_17_Time_22_ms_(95.17%)_Space_47.2_MB_(6.13%)

import java.util.HashMap;
import java.util.Map;

public class Solution {
    public int subarraySum(int[] nums, int k) {
        int tempSum = 0;
        int ret = 0;
        Map sumCount = new HashMap<>();
        sumCount.put(0, 1);
        for (int i : nums) {
            tempSum += i;
            if (sumCount.containsKey(tempSum - k)) {
                ret += sumCount.get(tempSum - k);
            }
            if (sumCount.get(tempSum) != null) {
                sumCount.put(tempSum, sumCount.get(tempSum) + 1);
            } else {
                sumCount.put(tempSum, 1);
            }
        }
        return ret;
    }
}