11-15

• 盛水最多的容器

  

     

  从两边开始往中间缩小，较小的一条边移动 因为面积是由较小一边决定的（较大一边移动的话不可有比现在面积更大的了，因为高最高是较小边，宽还在缩小）

  int maxArea(vector<int>& height) {

      int len = height.size();

      int max = 0;

      int area = 0;

      int left = 0, right = len - 1;

      while (left < right) {

          area = min(height[left], height[right]) * (right - left);

          if (area > max) max = area;

          if (height[left] > height[right]) right--;

          else left++;

      }

      return max;

  }

     

• 整数转罗马数字

  

  1000 900 500 400

  100 90 50 40

  10 9 5 4

  各判断一次

  string intToRoman(int num) {

      string ans;

      int temp = num;

      int cnt = temp / 1000;

      temp = temp - cnt * 1000;

      while (cnt--) ans.push_back('M');

      if (temp >= 900) {

          ans.push_back('C');

          ans.push_back('M');

          temp -= 900;

      }

      if (temp >= 500) {

          ans.push_back('D');

          temp -= 500;

      }

      if (temp >= 400) {

          ans.push_back('C');

          ans.push_back('D');

          temp -= 400;

      }

      cnt = temp / 100;

      temp = temp - cnt * 100;

      while (cnt--)ans.push_back('C');

        

      if (temp >= 90) {

          ans.push_back('X');

          ans.push_back('C');

          temp -= 90;

      }

      if (temp >= 50) {

          ans.push_back('L');

          temp -= 50;

      }

      if (temp >= 40) {

          ans.push_back('X');

          ans.push_back('L');

          temp -= 40;

      }

      cnt = temp / 10;

      temp = temp - cnt * 10;

      while (cnt--)ans.push_back('X');

      if (temp >= 9) {

          ans.push_back('I');

          ans.push_back('X');

          temp -= 9;

      }

      if (temp >= 5) {

          ans.push_back('V');

          temp -= 5;

      }

      if (temp >= 4) {

          ans.push_back('I');

          ans.push_back('V');

          temp -= 4;

      }

      while (temp--) ans.push_back('I');

      return ans;

  }

     

• 罗马数字转整数

  不写题解了

     

• 最长公共前缀

  不写

     

• 三数之和