leetcode 之trap water（8）

这题不太好想。可以先扫描找到最高的柱子，然后分别处理两边。

int trapWater(int A[], int n)
      {
          int peak = 0;
          int max = 0;
          int water = 0;
          for (int i = 1; i < n; i++)
          {
              if (A[i]>A[max])max = i;
          }

          for (int i = 0; i < max; i++)
          {
              if (A[i]>peak)
                  peak = A[i];
              else
                  water += peak - A[i];
          }

          for (int j = n - 1; j > max; j--)
          {
              if (A[j]>peak)
                  peak = A[j];
              else
                  water += peak - A[j];
          }

          return water;
      }