3168-MinimumNumberOfChairsInAWaitingRoom.go

package main

// 3168. Minimum Number of Chairs in a Waiting Room
// You are given a string s. Simulate events at each second i:
//     1. If s[i] == 'E', a person enters the waiting room and takes one of the chairs in it.
//     2. If s[i] == 'L', a person leaves the waiting room, freeing up a chair.

// Return the minimum number of chairs needed so that a chair is available for every person who enters the waiting room given that it is initially empty.

// Example 1:
// Input: s = "EEEEEEE"
// Output: 7
// Explanation:
// After each second, a person enters the waiting room and no person leaves it. Therefore, a minimum of 7 chairs is needed.

// Example 2:
// Input: s = "ELELEEL"
// Output: 2
// Explanation:
// Let's consider that there are 2 chairs in the waiting room. The table below shows the state of the waiting room at each second.
// Second	Event	People in the Waiting Room	Available Chairs
// 0	Enter	1	1
// 1	Leave	0	2
// 2	Enter	1	1
// 3	Leave	0	2
// 4	Enter	1	1
// 5	Enter	2	0
// 6	Leave	1	1

// Example 3:
// Input: s = "ELEELEELLL"
// Output: 3
// Explanation:
// Let's consider that there are 3 chairs in the waiting room. The table below shows the state of the waiting room at each second.
// Second	Event	People in the Waiting Room	Available Chairs
// 0	Enter	1	2
// 1	Leave	0	3
// 2	Enter	1	2
// 3	Enter	2	1
// 4	Leave	1	2
// 5	Enter	2	1
// 6	Enter	3	0
// 7	Leave	2	1
// 8	Leave	1	2
// 9	Leave	0	3

// Constraints:
//     1 <= s.length <= 50
//     s consists only of the letters 'E' and 'L'.
//     s represents a valid sequence of entries and exits.

import "fmt"

func minimumChairs(s string) int {
    res, count := 0, 0
    max := func (x, y int) int { if x > y { return x; }; return y; }
    for _, v := range s {
        if 'E' == v {
            count++
        } else if 'L' == v {
            count--
        }
        res = max(res, count)
    }
    return res
}

func main() {
    // Example 1:
    // Input: s = "EEEEEEE"
    // Output: 7
    // Explanation:
    // After each second, a person enters the waiting room and no person leaves it. Therefore, a minimum of 7 chairs is needed.
    fmt.Println(minimumChairs("EEEEEEE")) // 7
    // Example 2:
    // Input: s = "ELELEEL"
    // Output: 2
    // Explanation:
    // Let's consider that there are 2 chairs in the waiting room. The table below shows the state of the waiting room at each second.
    // Second	Event	People in the Waiting Room	Available Chairs
    // 0	Enter	1	1
    // 1	Leave	0	2
    // 2	Enter	1	1
    // 3	Leave	0	2
    // 4	Enter	1	1
    // 5	Enter	2	0
    // 6	Leave	1	1
    fmt.Println(minimumChairs("ELELEEL")) // 2
    // Example 3:
    // Input: s = "ELEELEELLL"
    // Output: 3
    // Explanation:
    // Let's consider that there are 3 chairs in the waiting room. The table below shows the state of the waiting room at each second.
    // Second	Event	People in the Waiting Room	Available Chairs
    // 0	Enter	1	2
    // 1	Leave	0	3
    // 2	Enter	1	2
    // 3	Enter	2	1
    // 4	Leave	1	2
    // 5	Enter	2	1
    // 6	Enter	3	0
    // 7	Leave	2	1
    // 8	Leave	1	2
    // 9	Leave	0	3
    fmt.Println(minimumChairs("ELEELEELLL")) // 3
}