167 Two Sum-Input array is sorted， 125 Valid Palindrome，344

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        //二分查找
        vector<int> result;
        int n = numbers.size();
        for(int i=0; i<n;i++){
            int second = target - numbers[i];
            int l = i+1, r = n-1;
            while(l<=r){
                int mid = (l+r)/2;
                if(second < numbers[mid]){
                    //在左半部分
                    r = mid-1;
                }
                else if(second > numbers[mid]){
                    //在右半部分
                    l = mid+1;
                }
                else{
                    //返回索引，从1开始
                    result.push_back(i+1);
                    result.push_back(mid+1);
                    break;
                }
            }
            if(result.size()==2) break;
        }
        return result;
    }
};

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        int n = numbers.size();
        int l = 0, r = n-1;
        while(l<r){
            if(numbers[l] + numbers[r] == target){
                int res[2] = {l+1, r+1};
                return vector<int>(res, res+2);
            }
            else if(numbers[l] + numbers[r] < target)
                l++;
            else
                r--;
        }
        throw invalid_argument("The input has no solution.");
    }
};

#include <ctype.h>
class Solution {
public:
    bool isPalindrome(string s) {
        int l = 0, r = s.size()-1;
        while(l<r){
            //跳过非字母和数字的字符
            while(!isalnum(s[l]) && l<r)
               l++;
            while(!isalnum(s[r]) && l<r)
               r--;
            //将字母或数字都转化为大写来比较是否相同
            if(toupper(s[l]) != toupper(s[r]))
               return false;
            l++;
            r--;
        }
        return true;
    }
};

class Solution {
public:
    string reverseString(string s) {
        int l = 0, r = s.size()-1;
        int mid = (l+r)/2;
        for(int i=0;i<=mid;i++){
            swap(s[l], s[r]);
            l++;
            r--;
        }
        return s;
    }
};

class Solution {
public:
    bool is_vowel(char c){
        if((c==‘a‘)||(c==‘e‘)||(c==‘i‘)||(c==‘o‘)||(c==‘u‘)||(c==‘A‘)||(c==‘E‘)||(c==‘I‘)||(c==‘O‘)||(c==‘U‘))
            return true;
        else 
            return false;
    }
    string reverseVowels(string s) {
        int n = s.size();
        int l = 0, r = n-1;
        
        while(l<r){
            while(!is_vowel(s[l]) && l<r)
                l++;
            while(!is_vowel(s[r]) && l<r)
                r--;
            swap(s[l], s[r]);
            l++;
            r--;
        }
        return s;
    }
};

class Solution {
public:
int maxArea(vector<int> &height) {
    int m = 0;
    int i = 0, j = height.size() - 1;
    while (i < j) {
        //m = max(m, (j - i) * min(height[i], height[j]));
        //height[i] < height[j] ? i++ : j--;
        if(height[i] < height[j]){
            m = max(m, (j - i) * height[i]);
            i++;
        }
        else{
             m = max(m, (j - i) * height[j]);
             j--;
        }
    }
    return m;
}
};