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Formatted question description: https://leetcode.ca/all/2213.html

2213. Longest Substring of One Repeating Character

  • Difficulty: Hard.
  • Related Topics: Array, String, Segment Tree, Ordered Set.
  • Similar Questions: Merge Intervals, Longest Repeating Character Replacement, Consecutive Characters, Create Sorted Array through Instructions.

Problem

You are given a 0-indexed string s. You are also given a 0-indexed string queryCharacters of length k and a 0-indexed array of integer indices queryIndices of length k, both of which are used to describe k queries.

The ith query updates the character in s at index queryIndices[i] to the character queryCharacters[i].

Return an array lengths of length **k where** lengths[i] is the **length of the longest substring of s consisting of only one repeating character after the** ith query** is performed.**

  Example 1:

Input: s = "babacc", queryCharacters = "bcb", queryIndices = [1,3,3]
Output: [3,3,4]
Explanation: 
- 1st query updates s = "bbbacc". The longest substring consisting of one repeating character is "bbb" with length 3.
- 2nd query updates s = "bbbccc". 
  The longest substring consisting of one repeating character can be "bbb" or "ccc" with length 3.
- 3rd query updates s = "bbbbcc". The longest substring consisting of one repeating character is "bbbb" with length 4.
Thus, we return [3,3,4].

Example 2:

Input: s = "abyzz", queryCharacters = "aa", queryIndices = [2,1]
Output: [2,3]
Explanation:
- 1st query updates s = "abazz". The longest substring consisting of one repeating character is "zz" with length 2.
- 2nd query updates s = "aaazz". The longest substring consisting of one repeating character is "aaa" with length 3.
Thus, we return [2,3].

  Constraints:

  • 1 <= s.length <= 105

  • s consists of lowercase English letters.

  • k == queryCharacters.length == queryIndices.length

  • 1 <= k <= 105

  • queryCharacters consists of lowercase English letters.

  • 0 <= queryIndices[i] < s.length

Solution

  • class Solution {
    static class TreeNode {
        int start;
        int end;
        char leftChar;
        int leftCharLen;
        char rightChar;
        int rightCharLen;
        int max;
        TreeNode left;
        TreeNode right;

        TreeNode(int start, int end) {
            this.start = start;
            this.end = end;
            left = null;
            right = null;
        }
    }

    public int[] longestRepeating(String s, String queryCharacters, int[] queryIndices) {
        char[] sChar = s.toCharArray();
        char[] qChar = queryCharacters.toCharArray();
        TreeNode root = buildTree(sChar, 0, sChar.length - 1);
        int[] result = new int[qChar.length];
        for (int i = 0; i < qChar.length; i++) {
            updateTree(root, queryIndices[i], qChar[i]);
            if (root != null) {
                result[i] = root.max;
            }
        }
        return result;
    }

    private TreeNode buildTree(char[] s, int from, int to) {
        if (from > to) {
            return null;
        }
        TreeNode root = new TreeNode(from, to);
        if (from == to) {
            root.max = 1;
            root.rightChar = root.leftChar = s[from];
            root.leftCharLen = root.rightCharLen = 1;
            return root;
        }
        int middle = from + (to - from) / 2;
        root.left = buildTree(s, from, middle);
        root.right = buildTree(s, middle + 1, to);
        updateNode(root);
        return root;
    }

    private void updateTree(TreeNode root, int index, char c) {
        if (root == null || root.start > index || root.end < index) {
            return;
        }
        if (root.start == index && root.end == index) {
            root.leftChar = root.rightChar = c;
            return;
        }
        updateTree(root.left, index, c);
        updateTree(root.right, index, c);
        updateNode(root);
    }

    private void updateNode(TreeNode root) {
        if (root == null) {
            return;
        }
        root.leftChar = root.left.leftChar;
        root.leftCharLen = root.left.leftCharLen;
        root.rightChar = root.right.rightChar;
        root.rightCharLen = root.right.rightCharLen;
        root.max = Math.max(root.left.max, root.right.max);
        if (root.left.rightChar == root.right.leftChar) {
            int len = root.left.rightCharLen + root.right.leftCharLen;
            if (root.left.leftChar == root.left.rightChar
                    && root.left.leftCharLen == root.left.end - root.left.start + 1) {
                root.leftCharLen = len;
            }
            if (root.right.leftChar == root.right.rightChar
                    && root.right.leftCharLen == root.right.end - root.right.start + 1) {
                root.rightCharLen = len;
            }
            root.max = Math.max(root.max, len);
        }
    }
}

############

class Node {
    int l;
    int r;
    int size;
    int lmx;
    int rmx;
    int mx;
    char lc;
    char rc;
}

class SegmentTree {
    private String s;
    private Node[] tr;

    public SegmentTree(String s) {
        int n = s.length();
        this.s = s;
        tr = new Node[n << 2];
        for (int i = 0; i < tr.length; ++i) {
            tr[i] = new Node();
        }
        build(1, 1, n);
    }

    public void build(int u, int l, int r) {
        tr[u].l = l;
        tr[u].r = r;
        if (l == r) {
            tr[u].lmx = 1;
            tr[u].rmx = 1;
            tr[u].mx = 1;
            tr[u].size = 1;
            tr[u].lc = s.charAt(l - 1);
            tr[u].rc = s.charAt(l - 1);
            return;
        }
        int mid = (l + r) >> 1;
        build(u << 1, l, mid);
        build(u << 1 | 1, mid + 1, r);
        pushup(u);
    }

    void modify(int u, int x, char v) {
        if (tr[u].l == x && tr[u].r == x) {
            tr[u].lc = v;
            tr[u].rc = v;
            return;
        }
        int mid = (tr[u].l + tr[u].r) >> 1;
        if (x <= mid) {
            modify(u << 1, x, v);
        } else {
            modify(u << 1 | 1, x, v);
        }
        pushup(u);
    }

    Node query(int u, int l, int r) {
        if (tr[u].l >= l && tr[u].r <= r) {
            return tr[u];
        }
        int mid = (tr[u].l + tr[u].r) >> 1;
        if (r <= mid) {
            return query(u << 1, l, r);
        }
        if (l > mid) {
            return query(u << 1 | 1, l, r);
        }
        Node ans = new Node();
        Node left = query(u << 1, l, r);
        Node right = query(u << 1 | 1, l, r);
        pushup(ans, left, right);
        return ans;
    }

    void pushup(Node root, Node left, Node right) {
        root.lc = left.lc;
        root.rc = right.rc;
        root.size = left.size + right.size;

        root.mx = Math.max(left.mx, right.mx);
        root.lmx = left.lmx;
        root.rmx = right.rmx;

        if (left.rc == right.lc) {
            if (left.lmx == left.size) {
                root.lmx += right.lmx;
            }
            if (right.rmx == right.size) {
                root.rmx += left.rmx;
            }
            root.mx = Math.max(root.mx, left.rmx + right.lmx);
        }
    }

    void pushup(int u) {
        pushup(tr[u], tr[u << 1], tr[u << 1 | 1]);
    }
}

class Solution {
    public int[] longestRepeating(String s, String queryCharacters, int[] queryIndices) {
        SegmentTree tree = new SegmentTree(s);
        int k = queryCharacters.length();
        int[] ans = new int[k];
        for (int i = 0; i < k; ++i) {
            int x = queryIndices[i] + 1;
            char c = queryCharacters.charAt(i);
            tree.modify(1, x, c);
            ans[i] = tree.query(1, 1, s.length()).mx;
        }
        return ans;
    }
}

  • class Node:
    def __init__(self):
        self.l = 0
        self.r = 0
        self.lmx = 0
        self.rmx = 0
        self.mx = 0
        self.size = 0
        self.lc = None
        self.rc = None


N = 100010
tr = [Node() for _ in range(N << 2)]


class SegmentTree:
    def __init__(self, s):
        n = len(s)
        self.s = s
        self.build(1, 1, n)

    def build(self, u, l, r):
        tr[u].l = l
        tr[u].r = r
        if l == r:
            tr[u].lmx = tr[u].rmx = tr[u].mx = tr[u].size = 1
            tr[u].lc = tr[u].rc = self.s[l - 1]
            return
        mid = (l + r) >> 1
        self.build(u << 1, l, mid)
        self.build(u << 1 | 1, mid + 1, r)
        self.pushup(u)

    def modify(self, u, x, v):
        if tr[u].l == x and tr[u].r == x:
            tr[u].lc = tr[u].rc = v
            return
        mid = (tr[u].l + tr[u].r) >> 1
        if x <= mid:
            self.modify(u << 1, x, v)
        else:
            self.modify(u << 1 | 1, x, v)
        self.pushup(u)

    def query(self, u, l, r):
        if tr[u].l >= l and tr[u].r <= r:
            return tr[u]
        mid = (tr[u].l + tr[u].r) >> 1
        if r <= mid:
            return self.query(u << 1, l, r)
        if l > mid:
            return self.query(u << 1 | 1, l, r)
        left, right = self.query(u << 1, l, r), self.query(u << 1 | 1, l, r)
        ans = Node()
        self._pushup(ans, left, right)
        return ans

    def _pushup(self, root, left, right):
        root.lc, root.rc = left.lc, right.rc
        root.size = left.size + right.size

        root.mx = max(left.mx, right.mx)
        root.lmx, root.rmx = left.lmx, right.rmx

        if left.rc == right.lc:
            if left.lmx == left.size:
                root.lmx += right.lmx
            if right.rmx == right.size:
                root.rmx += left.rmx
            root.mx = max(root.mx, left.rmx + right.lmx)

    def pushup(self, u):
        self._pushup(tr[u], tr[u << 1], tr[u << 1 | 1])


class Solution:
    def longestRepeating(
        self, s: str, queryCharacters: str, queryIndices: List[int]
    ) -> List[int]:
        tree = SegmentTree(s)
        k = len(queryIndices)
        ans = []
        for i, c in enumerate(queryCharacters):
            x = queryIndices[i] + 1
            tree.modify(1, x, c)
            ans.append(tree.query(1, 1, len(s)).mx)
        return ans

############

# 2213. Longest Substring of One Repeating Character
# https://leetcode.com/problems/longest-substring-of-one-repeating-character/

from sortedcontainers import SortedList

class Solution:
    def longestRepeating(self, s: str, qc: str, qi: List[int]) -> List[int]:
        M = 10 ** 6
        n = len(s)
        k = len(qc)
        
        s = list(s)
        
        sl = SortedList()
        h = SortedList()
        
        curr = 0
        
        for x, group in groupby(s):
            length = sum(1 for c in group)
            sl.add((curr, curr + length - 1))
            h.add(length)
            curr += length
        
        def add(x, y):
            sl.add((x, y))
            h.add(y - x + 1)
        
        def remove(x, y):
            sl.remove((x, y))
            h.remove(y - x + 1)
        
        def split(i):
            index = sl.bisect_right((i, M)) - 1
        
            left, right = sl[index]
            remove(left, right)
            
            if left != i:
                add(left, i - 1)
                
            add(i, i)
            
            if right != i:
                add(i + 1, right)
        
        def merge(index):
            if index + 1 >= len(sl): return
            
            left1, right1 = sl[index]
            left2, right2 = sl[index + 1]
            
            if s[right1] != s[left2]: return
            
            remove(left1, right1)
            remove(left2, right2)
            add(left1, right2)
            
        res = []
        
        for i, c in zip(qi, qc):
            if s[i] == c:
                res.append(h[-1])
                continue
            
            split(i)
            
            index = sl.bisect_right((i, M)) - 1
            
            s[i] = c
            merge(index)
            
            if index - 1 >= 0:
                merge(index - 1)
            
            res.append(h[-1])
        
        return res
            
        


  • class Node {
public:
    int l, r, size, lmx, rmx, mx;
    char lc, rc;
};

class SegmentTree {
private:
    string s;
    vector<Node*> tr;

public:
    SegmentTree(string& s) {
        this->s = s;
        int n = s.size();
        tr.resize(n << 2);
        for (int i = 0; i < tr.size(); ++i) tr[i] = new Node();
        build(1, 1, n);
    }

    void build(int u, int l, int r) {
        tr[u]->l = l;
        tr[u]->r = r;
        if (l == r) {
            tr[u]->lmx = tr[u]->rmx = tr[u]->mx = tr[u]->size = 1;
            tr[u]->lc = tr[u]->rc = s[l - 1];
            return;
        }
        int mid = (l + r) >> 1;
        build(u << 1, l, mid);
        build(u << 1 | 1, mid + 1, r);
        pushup(u);
    }

    void modify(int u, int x, char v) {
        if (tr[u]->l == x && tr[u]->r == x) {
            tr[u]->lc = tr[u]->rc = v;
            return;
        }
        int mid = (tr[u]->l + tr[u]->r) >> 1;
        if (x <= mid)
            modify(u << 1, x, v);
        else
            modify(u << 1 | 1, x, v);
        pushup(u);
    }

    Node* query(int u, int l, int r) {
        if (tr[u]->l >= l && tr[u]->r <= r) return tr[u];
        int mid = (tr[u]->l + tr[u]->r) >> 1;
        if (r <= mid) return query(u << 1, l, r);
        if (l > mid) query(u << 1 | 1, l, r);
        Node* ans = new Node();
        Node* left = query(u << 1, l, r);
        Node* right = query(u << 1 | 1, l, r);
        pushup(ans, left, right);
        return ans;
    }

    void pushup(Node* root, Node* left, Node* right) {
        root->lc = left->lc;
        root->rc = right->rc;
        root->size = left->size + right->size;

        root->mx = max(left->mx, right->mx);
        root->lmx = left->lmx;
        root->rmx = right->rmx;

        if (left->rc == right->lc) {
            if (left->lmx == left->size) root->lmx += right->lmx;
            if (right->rmx == right->size) root->rmx += left->rmx;
            root->mx = max(root->mx, left->rmx + right->lmx);
        }
    }

    void pushup(int u) {
        pushup(tr[u], tr[u << 1], tr[u << 1 | 1]);
    }
};

class Solution {
public:
    vector<int> longestRepeating(string s, string queryCharacters, vector<int>& queryIndices) {
        SegmentTree* tree = new SegmentTree(s);
        int k = queryCharacters.size();
        vector<int> ans(k);
        for (int i = 0; i < k; ++i) {
            int x = queryIndices[i] + 1;
            tree->modify(1, x, queryCharacters[i]);
            ans[i] = tree->query(1, 1, s.size())->mx;
        }
        return ans;
    }
};

  • type segmentTree struct {
	str []byte
	mx  []int
	lmx []int
	rmx []int
}

func newSegmentTree(s string) *segmentTree {
	n := len(s)
	t := &segmentTree{
		str: []byte(s),
		mx:  make([]int, n<<2),
		lmx: make([]int, n<<2),
		rmx: make([]int, n<<2),
	}
	t.build(0, 0, n-1)
	return t
}

func (t *segmentTree) build(x, l, r int) {
	if l == r {
		t.lmx[x] = 1
		t.rmx[x] = 1
		t.mx[x] = 1
		return
	}
	m := int(uint(l+r) >> 1)
	t.build(x*2+1, l, m)
	t.build(x*2+2, m+1, r)
	t.pushup(x, l, m, r)
}

func (t *segmentTree) pushup(x, l, m, r int) {
	lch, rch := x*2+1, x*2+2
	t.lmx[x] = t.lmx[lch]
	t.rmx[x] = t.rmx[rch]
	t.mx[x] = max(t.mx[lch], t.mx[rch])
	// can be merged
	if t.str[m] == t.str[m+1] {
		if t.lmx[lch] == m-l+1 {
			t.lmx[x] += t.lmx[rch]
		}
		if t.rmx[rch] == r-m {
			t.rmx[x] += t.rmx[lch]
		}
		t.mx[x] = max(t.mx[x], t.rmx[lch]+t.lmx[rch])
	}
}

func (t *segmentTree) update(x, l, r, pos int, val byte) {
	if l == r {
		t.str[pos] = val
		return
	}
	m := int(uint(l+r) >> 1)
	if pos <= m {
		t.update(x*2+1, l, m, pos, val)
	} else {
		t.update(x*2+2, m+1, r, pos, val)
	}
	t.pushup(x, l, m, r)
}

func max(x, y int) int {
	if x > y {
		return x
	}
	return y
}

func longestRepeating(s string, queryCharacters string, queryIndices []int) []int {
	ans := make([]int, len(queryCharacters))
	t := newSegmentTree(s)
	n := len(s)
	for i, c := range queryCharacters {
		t.update(0, 0, n-1, queryIndices[i], byte(c))
		ans[i] = t.mx[0]
	}
	return ans
}

Explain:

nope.

Complexity:

  • Time complexity : O(n).
  • Space complexity : O(n).

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