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174 lines (133 loc) · 4.94 KB
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package Java_Bootcamp.DSA_Patterns.SubArray;
import java.util.Arrays;
import java.util.HashMap;
public class Programs {
public static void main(String[] args) {
int[] arr = {2,1,5,1,3,2};
int target = 3;
// System.out.println(isSubArrayOfSumExist(arr,target));
// System.out.println(Arrays.toString(SubArrayOfSumIndices(arr,target)));
// System.out.println(isSubArrayOfSumExistByTwoPointer(arr,target));
// smallestSubArrayOfSum(arr,target);
smallestSubArrayOfK(arr,target);
}
static void smallestSubArrayOfK(int[] arr, int k) {
int maxSum = Integer.MIN_VALUE;
for (int i = 0; i < arr.length-k+1; i++) {
int currentSum = 0;
for (int j = i; j < k; j++) {
currentSum += arr[j];
}
maxSum = Math.max(maxSum,currentSum);
}
System.out.println(maxSum);
}
static void smallestSubArrayOfSum(int[] arr, int sum) {
int minLen = Integer.MAX_VALUE;
for (int i = 0; i < arr.length; i++) {
int currentSum = 0;
for (int j = i; j < arr.length; j++) {
currentSum += arr[j];
if (currentSum == sum) {
int len = j - i + 1;
minLen = Math.min(minLen, len);
}
}
}
System.out.println("Length of Smallest Subarray: " + minLen);
}
static boolean isSubArrayOfSumExistByTwoPointer(int[] arr, int targetSum) {
int start = 0, end = 0;
int currentSum = 0;
while (end < arr.length) {
currentSum += arr[end];
while (currentSum > targetSum && start <= end) {
currentSum -= arr[start];
start++;
}
if (currentSum == targetSum) {
return true;
}
end++;
}
return false;
}
static int[] SubArrayOfSumIndices(int[] arr, int sum) {
for (int i = 0; i < arr.length; i++) {
int currentSum = 0;
for (int j = i; j < arr.length; j++) {
currentSum += arr[j];
if (currentSum == sum) {
return new int[]{i,j};
}
}
}
return new int[]{-1,-1};
}
static boolean isSubArrayOfSumExist(int[] arr, int sum) {
for (int i = 0; i < arr.length; i++) {
int currentSum = 0;
for (int j = i; j < arr.length; j++) {
currentSum += arr[j];
if (currentSum == sum) {
return true;
}
if (currentSum > sum)
break;
}
}
return false;
}
static void longestSubArrayOfSumByTwoPointer(int[] arr, int targetSum) {
// This is a Sliding Window technique — implemented using Two Pointers.
int start = 0, end = 0;
int currentSum = 0;
int maxLength = 0;
while (end < arr.length) {
currentSum += arr[end];
while (currentSum > targetSum && start <= end) {
currentSum -= arr[start];
start++;
}
if (currentSum == targetSum) {
maxLength = Math.max(maxLength, end - start + 1);
}
end++;
}
System.out.println("Length of Longest Subarray with sum " + targetSum + " is: " + maxLength);
}
static void longestSubArrayOfSumByHashMap(int[] arr, int targetSum) {
HashMap<Integer, Integer> prefixSumMap = new HashMap<>();
int currSum = 0;
int maxLength = 0;
for (int i = 0; i < arr.length; i++) {
currSum += arr[i];
if (currSum == targetSum) {
maxLength = i + 1;
}
if (prefixSumMap.containsKey(currSum - targetSum)) {
int length = i - prefixSumMap.get(currSum - targetSum);
maxLength = Math.max(maxLength, length);
}
// Store only the first occurrence of currSum
if (!prefixSumMap.containsKey(currSum)) {
prefixSumMap.put(currSum, i);
}
}
System.out.println("Length of Longest Subarray with sum " + targetSum + " is: " + maxLength);
}
static void longestSubArrayOfSum(int[] arr, int sum) {
int maxLen = 0;
for (int i = 0; i < arr.length; i++) {
int currentSum = 0;
for (int j = i; j < arr.length; j++) {
currentSum += arr[j];
if (currentSum == sum) {
int len = j - i + 1;
maxLen = Math.max(maxLen, len);
}
}
}
System.out.println("Length of Longest Subarray: " + maxLen);
}
}