Count and Say

class Solution {
public:
    string countAndSay(int n) {
        string cur = "1";
        for (int step = 1; step < n; ++step) {
            string nxt;
            for (int i = 0; i < (int)cur.size(); ) {
                int j = i;
                while (j < (int)cur.size() && cur[j] == cur[i]) ++j;
                nxt += to_string(j - i);
                nxt.push_back(cur[i]);
                i = j;
            }
            cur = std::move(nxt);
        }
        return cur;
    }
};

import "strconv"

func countAndSay(n int) string {
    cur := "1"
    for step := 1; step < n; step++ {
        var nxt []byte
        for i := 0; i < len(cur); {
            j := i
            for j < len(cur) && cur[j] == cur[i] {
                j++
            }
            nxt = append(nxt, []byte(strconv.Itoa(j-i))...)
            nxt = append(nxt, cur[i])
            i = j
        }
        cur = string(nxt)
    }
    return cur
}

class Solution:
    def countAndSay(self, n: int) -> str:
        cur = "1"
        for _ in range(n - 1):
            parts = []
            i = 0
            while i < len(cur):
                j = i
                while j < len(cur) and cur[j] == cur[i]:
                    j += 1
                parts.append(str(j - i))
                parts.append(cur[i])
                i = j
            cur = ''.join(parts)
        return cur

function countAndSay(n) {
    let cur = "1";
    for (let step = 1; step < n; step++) {
        const parts = [];
        let i = 0;
        while (i < cur.length) {
            let j = i;
            while (j < cur.length && cur[j] === cur[i]) j++;
            parts.push(String(j - i));
            parts.push(cur[i]);
            i = j;
        }
        cur = parts.join('');
    }
    return cur;
}

class Solution {
    public String countAndSay(int n) {
        String cur = "1";
        for (int step = 1; step < n; step++) {
            StringBuilder nxt = new StringBuilder();
            int i = 0;
            while (i < cur.length()) {
                int j = i;
                while (j < cur.length() && cur.charAt(j) == cur.charAt(i)) j++;
                nxt.append(j - i);
                nxt.append(cur.charAt(i));
                i = j;
            }
            cur = nxt.toString();
        }
        return cur;
    }
}

function countAndSay(n: number): string {
    let cur = "1";
    for (let step = 1; step < n; step++) {
        const parts: string[] = [];
        let i = 0;
        while (i < cur.length) {
            let j = i;
            while (j < cur.length && cur[j] === cur[i]) j++;
            parts.push(String(j - i));
            parts.push(cur[i]);
            i = j;
        }
        cur = parts.join('');
    }
    return cur;
}