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138 lines (102 loc) · 3.17 KB
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package DifferenceArrayTech;
import java.util.*;
public class ZeroArray2 {
// brute force
public static void main(String[] args) {
int[] nums = { 1, 2, 3, 4, 5 };
int[][] queries = { { 0, 2, 1 }, { 1, 2, 1 }, { 1, 1, 3 } };
findNumbersOfqueries(nums, queries);
}
// Brute force TLE
public static int findNumbersOfqueries(int[] nums, int[][] queries) {
int numbersOfqueries = 0;
for (int[] query : queries) {
int start = query[0];
int end = query[1];
int value = query[2];
for (int i = start; i <= end && i < nums.length; i++) {
nums[i] = Math.max(0, nums[i] - value);
}
numbersOfqueries++;
boolean isZeroArray = true;
for (int num : nums) {
if (num != 0) {
isZeroArray = false;
break;
}
}
if (isZeroArray)
return numbersOfqueries;
}
return -1;
}
//Better thana brtue TLE
public int minZeroArray(int[] nums, int[][] queries) {
// ✅ Step 0: Early check
boolean isAlreadyZero = true;
for (int num : nums) {
if (num != 0) {
isAlreadyZero = false;
break;
}
}
if (isAlreadyZero)
return 0;
for (int i = 0; i < queries.length; i++) {
if (isZeroArray(nums, queries, i)) {
return i + 1;
}
}
return -1;
}
//Optimal
public int minZeroArray1(int[] nums, int[][] queries) {
// ✅ Step 0: Early check
boolean isAlreadyZero = true;
for (int num : nums) {
if (num != 0) {
isAlreadyZero = false;
break;
}
}
if (isAlreadyZero)
return 0;
int l = 0;
int r = queries.length -1;
int k = -1;
while (l <= r) {
int mid = l + (r -l )/ 2;
if(isZeroArray(nums,queries,mid)){
k =mid + 1;
r = mid -1;
}else{
l = mid + 1;
}
}
return k;
}
public boolean isZeroArray(int[] nums, int[][] queries, int k) {
int n = nums.length;
// Step 1 create difference array
int[] diffArray = new int[n];
Arrays.fill(diffArray, 0);
for (int i = 0; i <= k; i++) {
int start = queries[i][0];
int end = queries[i][1];
int value = queries[i][2];
diffArray[start] += value;
if (end + 1 < n) {
diffArray[end + 1] -= value;
}
}
// commulative sum
int cumSum = 0;
for (int i = 0; i < n; i++) {
cumSum += diffArray[i];
diffArray[i] = cumSum;
if (nums[i] - diffArray[i] > 0)
return false; // nums[i] 0 nhi ban paya
}
return true;
}
}