HDU 1506 Largest Rectangle in a Histogram

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 100010;
18 int q[maxn] = {-1},w[maxn],tp,n,h;//w记录前面比自己大的元素个数
19 LL ans;
20 int main(){
21     while(scanf("%d",&n),n){
22         ans = tp = 0;
23         for(int i = 0; i <= n; i++){
24             if(i == n) h = 0;
25             else scanf("%d",&h);
26             if(h > q[tp]){
27                 q[++tp] = h;
28                 w[tp] = 1;
29             }else{
30                 LL cnt = 0;
31                 while(h <= q[tp]){
32                     ans = max(ans,(cnt+w[tp])*q[tp]);//每次找q中下降的
33                     cnt += w[tp--];
34                 }
35                 q[++tp] = h;
36                 w[tp] = ++cnt;//算上自己
37             }
38         }
39         printf("%I64d\n",ans);
40     }
41     return 0;
42 }