s4553711

class Solution {
public:
    int largestPalindrome(int n) {
        int l = pow(10, n-1), r = pow(10, n) - 1;
        for(int i = r; i>= 1; i--) {
            string s = to_string(i);
            string t = s;
            reverse(t.begin(), t.end());
            long ans = stol(s + t);
            for(long j = r; j * j >= ans; j--)

s4553711

class Solution {
public:
    int findRadius(vector<int>& houses, vector<int>& heaters) {
        if (heaters.size() == 0) return 0;
        sort(houses.begin(), houses.end());
        sort(heaters.begin(), heaters.end());
        int radius = 0;
        int index = 0;
        for(int i = 0; i < houses.size(); i++) {
            while(index + 1 < heaters.size() && abs(heaters[index+1] -  houses[i]) <= abs(heaters[index] - houses[i])) {

s4553711

class Solution {
public:
    int findNthDigit(int n) {
        long digit = 1, sum = 9;
        while(n > digit * sum) {
            n = n - digit * sum;
            sum *= 10;
            digit++;
        }
        int index = n % digit;

s4553711

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:

s4553711

class MinStack {
public:
    stack<int> all;
    stack<int> minsta;
    /** initialize your data structure here. */
    MinStack() {
        
    }
    
    void push(int x) {

s4553711

class Solution {
public:
    bool judgeSquareSum(int c) {
        int half = (c >> 1), sb, b;
        for(int a = 0; a * a <= half; a++) {
            sb = c - a * a;
            b = sqrt(sb);
            if (b * b == sb) return true;
        }
        return false;

s4553711

class Solution {
public:
    string countAndSay(int n) {
        if (n == 0) return "";
        string res = "1";
        while (--n) {
            string cur = "";
            //cout << "new: n: " << n << ", res: " << res << endl;
            for(int i = 0; i < res.size(); i++) {
                int count = 1;

s4553711

class Solution {
public:
    int lengthOfLastWord(string s) {
        int len = 0, tail = s.length() - 1;
        while (tail >= 0 && s[tail] == ' ') tail--;
        while (tail >= 0 && s[tail] != ' ') {
            len++;
            tail--;
        }
        return len;

s4553711

class Solution {
private:
public:
    void DFS(string s, int start, int step, string ip, vector<string>& ans) {
        if (start == s.size() && step == 4) {
            ip.erase(ip.end() - 1);
            ans.push_back(ip);
            return;
        }
        if (s.size()-start >(4-step)*3) return;

s4553711

class Solution {
public:
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<vector<int>> res;
        vector<int> curr;
        bk(res, candidates, curr, 0, target);
        return res;
    }
    void bk(vector<vector<int>>& ans, vector<int>& candidates, vector<int> curr, int last_use, int rest_target) {