# Maximal Points From Deleting Two Character Substrings- Google Top Interview Questions

### Problem Statement :

```You are given a string s containing "1"s and "0"s and integers zeroone and onezero.

In one operation you can remove any substring "01" and receive zeroone points.

Or you can remove any substring "10" and receive onezero points.

Return the maximum number of points you can receive, given that you can make any number of operations.

Constraints

n ≤ 100,000 where n is the length of s

Example 1

Input

s = "101010"

zeroone = 3

onezero = 1

Output

7

Explanation

We can delete "01" twice to receive 3 points each. The resulting string then becomes "10" and then you
can delete it to receive 1 point.```

### Solution :

```                        ```Solution in C++ :

int solve(string s, int zeroone, int onezero) {
bool flag = 0;
if (zeroone > onezero) flag = 1;
stack<char> st;
int ans = 0;
for (int i = 0; i < s.size(); i++) {
if (st.empty()) {
st.push(s[i]);
continue;
}
if (s[i] == '0' && st.top() == '1' && !flag) {
ans += onezero;
st.pop();
} else if (s[i] == '1' && st.top() == '0' && flag) {
ans += zeroone;
st.pop();
} else
st.push(s[i]);
}
int one = 0, zero = 0;
while (!st.empty()) {
if (st.top() == '0') zero++;
if (st.top() == '1') one++;
st.pop();
}
if (flag)
ans += (onezero * min(zero, one));
else
ans += (zeroone * min(zero, one));
return ans;
}```
```

```                        ```Solution in Java :

import java.util.*;

class Solution {
public int solve(String s, int A, int B) {
int N = s.length();
int[] nums = new int[N];
int X = 0;
for (int i = 0; i < N; i++) {
nums[i] = s.charAt(i) - '0';
if (nums[i] == 0)
X++;
}
X = Math.min(X, N - X);
if (A < B) {
int temp = A;
A = B;
B = temp;
for (int i = 0; i < N; i++) {
nums[i] = 1 - nums[i];
}
}
int zero = 0;
int get = 0;
for (int i = 0; i < N; i++) {
if (nums[i] == 0) {
zero++;
} else {
if (zero > 0) {
zero--;
get++;
}
}
}
int ans = get * A + (X - get) * B;
return ans;
}
}```
```

```                        ```Solution in Python :

class Solution:
def solve(self, S, pts01, pts10):
A = list(map(int, S))
if pts01 < pts10:
pts01, pts10 = pts10, pts01
for i in range(len(A)):
A[i] ^= 1

ans = 0
stack = []
for x in A:
if stack and stack[-1] < x:
stack.pop()
ans += pts01
else:
stack.append(x)

ans += pts10 * min(stack.count(0), stack.count(1))
return ans```
```

## Binary Search Tree : Lowest Common Ancestor

You are given pointer to the root of the binary search tree and two values v1 and v2. You need to return the lowest common ancestor (LCA) of v1 and v2 in the binary search tree. In the diagram above, the lowest common ancestor of the nodes 4 and 6 is the node 3. Node 3 is the lowest node which has nodes and as descendants. Function Description Complete the function lca in the editor b

## Swap Nodes [Algo]

A binary tree is a tree which is characterized by one of the following properties: It can be empty (null). It contains a root node only. It contains a root node with a left subtree, a right subtree, or both. These subtrees are also binary trees. In-order traversal is performed as Traverse the left subtree. Visit root. Traverse the right subtree. For this in-order traversal, start from

## Kitty's Calculations on a Tree

Kitty has a tree, T , consisting of n nodes where each node is uniquely labeled from 1 to n . Her friend Alex gave her q sets, where each set contains k distinct nodes. Kitty needs to calculate the following expression on each set: where: { u ,v } denotes an unordered pair of nodes belonging to the set. dist(u , v) denotes the number of edges on the unique (shortest) path between nodes a

## Is This a Binary Search Tree?

For the purposes of this challenge, we define a binary tree to be a binary search tree with the following ordering requirements: The data value of every node in a node's left subtree is less than the data value of that node. The data value of every node in a node's right subtree is greater than the data value of that node. Given the root node of a binary tree, can you determine if it's also a

## Square-Ten Tree

The square-ten tree decomposition of an array is defined as follows: The lowest () level of the square-ten tree consists of single array elements in their natural order. The level (starting from ) of the square-ten tree consists of subsequent array subsegments of length in their natural order. Thus, the level contains subsegments of length , the level contains subsegments of length , the

## Balanced Forest

Greg has a tree of nodes containing integer data. He wants to insert a node with some non-zero integer value somewhere into the tree. His goal is to be able to cut two edges and have the values of each of the three new trees sum to the same amount. This is called a balanced forest. Being frugal, the data value he inserts should be minimal. Determine the minimal amount that a new node can have to a