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Merged
merged 5 commits into from
Apr 29, 2025
Merged

Improved tasks 3510, 3515 #1970

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fc37d31
Improved tasks 3510, 3515
javadev Apr 29, 2025
f35e25c
Fixed sonar
javadev Apr 29, 2025
f6f87cf
Added tests
javadev Apr 29, 2025
7c52280
Improved task
javadev Apr 29, 2025
ff1719f
Added test
javadev Apr 29, 2025
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174 changes: 91 additions & 83 deletions src/main/java/g3501_3600/s3510_minimum_pair_removal_to_sort_array_ii/Solution.java
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Original file line number Diff line number Diff line change
@@ -1,104 +1,112 @@
package g3501_3600.s3510_minimum_pair_removal_to_sort_array_ii;

// #Hard #Array #Hash_Table #Heap_Priority_Queue #Simulation #Linked_List #Ordered_Set
// #Doubly_Linked_List #2025_04_09_Time_289_ms_(99.58%)_Space_82.88_MB_(17.23%)
// #Doubly_Linked_List #2025_04_29_Time_278_ms_(98.94%)_Space_70.90_MB_(68.88%)

public class Solution {
private static class Segment {
private final int start;
private final int end;
private Segment left;
private Segment right;
private int lIdx;
private long lNum;
private int rIdx;
private long rNum;
private boolean ok;
private long minSum;
private int li;
private int ri;
import java.util.Arrays;

public static Segment init(int[] arr) {
return new Segment(arr, 0, arr.length - 1);
public class Solution {
public int minimumPairRemoval(int[] nums) {
if (nums.length == 1) {
return 0;
}

public Segment(int[] arr, int s, int e) {
start = s;
end = e;
if (s >= e) {
lIdx = rIdx = s;
lNum = rNum = arr[s];
minSum = Long.MAX_VALUE;
ok = true;
return;
int size = (int) Math.pow(2, Math.ceil(Math.log(nums.length - 1.0) / Math.log(2)));
long[] segment = new long[size * 2 - 1];
Arrays.fill(segment, Long.MAX_VALUE);
int[] lefts = new int[size * 2 - 1];
int[] rights = new int[size * 2 - 1];
long[] sums = new long[nums.length];
Arrays.fill(sums, Long.MAX_VALUE / 2);
int[][] arrIdxToSegIdx = new int[nums.length][];
sums[0] = nums[0];
int count = 0;
arrIdxToSegIdx[0] = new int[] {-1, size - 1};
for (int i = 1; i < nums.length; i++) {
if (nums[i] < nums[i - 1]) {
count++;
}
int mid = s + ((e - s) >> 1);
left = new Segment(arr, s, mid);
right = new Segment(arr, mid + 1, e);
merge();
lefts[size + i - 2] = i - 1;
rights[size + i - 2] = i;
segment[size + i - 2] = nums[i - 1] + (long) nums[i];
arrIdxToSegIdx[i] = new int[] {size + i - 2, size + i - 1};
sums[i] = nums[i];
}

private void merge() {
lIdx = left.lIdx;
lNum = left.lNum;
rIdx = right.rIdx;
rNum = right.rNum;
ok = left.ok && right.ok && left.rNum <= right.lNum;
minSum = left.minSum;
li = left.li;
ri = left.ri;
if (left.rNum + right.lNum < minSum) {
minSum = left.rNum + right.lNum;
li = left.rIdx;
ri = right.lIdx;
}
if (right.minSum < minSum) {
minSum = right.minSum;
li = right.li;
ri = right.ri;
}
arrIdxToSegIdx[nums.length - 1][1] = -1;
for (int i = size - 2; i >= 0; i--) {
int l = 2 * i + 1;
int r = 2 * i + 2;
segment[i] = Math.min(segment[l], segment[r]);
}
return getRes(count, segment, lefts, rights, sums, arrIdxToSegIdx);
}

public void update(int i, long n) {
if (start <= i && end >= i) {
if (start >= end) {
lNum = rNum = n;
private int getRes(
int count,
long[] segment,
int[] lefts,
int[] rights,
long[] sums,
int[][] arrIdxToSegIdx) {
int res = 0;
while (count > 0) {
int segIdx = 0;
while (2 * segIdx + 1 < segment.length) {
int l = 2 * segIdx + 1;
int r = 2 * segIdx + 2;
if (segment[l] <= segment[r]) {
segIdx = l;
} else {
left.update(i, n);
right.update(i, n);
merge();
segIdx = r;
}
}
}

public Segment remove(int i) {
if (start > i || end < i) {
return this;
} else if (start >= end) {
return null;
int arrIdxL = lefts[segIdx];
int arrIdxR = rights[segIdx];
long numL = sums[arrIdxL];
long numR = sums[arrIdxR];
if (numL > numR) {
count--;
}
left = left.remove(i);
right = right.remove(i);
if (null == left) {
return right;
} else if (null == right) {
return left;
long newSum = sums[arrIdxL] = sums[arrIdxL] + sums[arrIdxR];
int[] leftPointer = arrIdxToSegIdx[arrIdxL];
int[] rightPointer = arrIdxToSegIdx[arrIdxR];
int prvSegIdx = leftPointer[0];
int nextSegIdx = rightPointer[1];
leftPointer[1] = nextSegIdx;
if (prvSegIdx != -1) {
int l = lefts[prvSegIdx];
if (sums[l] > numL && sums[l] <= newSum) {
count--;
} else if (sums[l] <= numL && sums[l] > newSum) {
count++;
}
modify(segment, prvSegIdx, sums[l] + newSum);
}
if (nextSegIdx != -1) {
int r = rights[nextSegIdx];
if (numR > sums[r] && newSum <= sums[r]) {
count--;
} else if (numR <= sums[r] && newSum > sums[r]) {
count++;
}
modify(segment, nextSegIdx, newSum + sums[r]);
lefts[nextSegIdx] = arrIdxL;
}
merge();
return this;
modify(segment, segIdx, Long.MAX_VALUE);
res++;
}
return res;
}

public int minimumPairRemoval(int[] nums) {
Segment root = Segment.init(nums);
int res = 0;
while (!root.ok) {
int l = root.li;
int r = root.ri;
root.update(l, root.minSum);
root = root.remove(r);
res++;
private void modify(long[] segment, int idx, long num) {
if (segment[idx] == num) {
return;
}
segment[idx] = num;
while (idx != 0) {
idx = (idx - 1) / 2;
int l = 2 * idx + 1;
int r = 2 * idx + 2;
segment[idx] = Math.min(segment[l], segment[r]);
}
return res;
}
}
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