LeetCode: Largest Rectangle in Histogram

没想出来，看了网上答案再改了改

 1 class Solution {
 2 public:
 3     struct node {
 4         int left;
 5         int right;
 6     };
 7     int largestRectangleArea(vector<int> &height) {
 8         // Start typing your C/C++ solution below
 9         // DO NOT write int main() function
10         int n = height.size();
11         vector<struct node> record(n);
12         for (int i = 0; i < n; i++) {
13             record[i].left = i;
14             while (record[i].left > 0 && height[i] <= height[record[i].left-1])
15                 record[i].left = record[record[i].left-1].left;            
16         }
17         for (int i = n-1; i >= 0; i--) {
18             record[i].right = i;
19             while (record[i].right < n-1 && height[i] <= height[record[i].right+1])
20                 record[i].right = record[record[i].right+1].right;
21         }
22         int largest = 0;
23         for (int i = 0; i < n; i++)
24             largest = max(largest, height[i] * (record[i].right - record[i].left + 1));
25         return largest;
26     }
27 };

再贴段容易理解的代码

 1 class Solution {
 2 public:
 3     int largestRectangleArea(vector<int> &h) {
 4         stack<int> S;
 5         h.push_back(0);
 6         int sum = 0;
 7         for (int i = 0; i < h.size(); i++) {
 8             if (S.empty() || h[i] > h[S.top()]) S.push(i);
 9             else {
10                 int tmp = S.top();
11                 S.pop();
12                 sum = max(sum, h[tmp]*(S.empty()? i : i-S.top()-1));
13                 i--;
14             }
15         }
16         return sum;
17     }
18 };

 1 public class Solution {
 2     public int LargestRectangleArea(int[] height) {
 3         Stack<int> S = new Stack<int>();
 4         int[] heights = new int[height.Length+1];
 5         int sum = 0;
 6         Array.Copy(height, heights, height.Length);
 7         for (int i = 0; i < heights.Length; i++) {
 8             if (S.Count == 0 || heights[i] > heights[S.Peek()]) S.Push(i);
 9             else {
10                 int peek = S.Peek();
11                 S.Pop();
12                 sum = Math.Max(sum, heights[peek]*(S.Count == 0? i : i-S.Peek()-1));
13                 i--;
14             }
15         }
16         return sum;
17     }
18 }

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posted @ 2013-04-02 05:11 ying_vincent 阅读(241) 评论(0) 收藏举报

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