标签:lse rect nbsp iostream stream top his class 长度
原题目链接:http://poj.org/problem?id=2559
用单调栈求任意每个区间的最小值及区间长度,为什么记录区间最小值呢?(木桶装水原理,装水量取决于最短木板长)。枚举每个区间,维护最大答案。
//自行百度单调栈
1 #include<iostream> 2 #include<cstdio> 3 #include<stack> 4 5 using namespace std; 6 7 stack<long long> le,ri; 8 int n; 9 struct kkk { 10 long long v,l,r; 11 long long xb; 12 }a[100001]; 13 14 void chushihua() { 15 for(int i = 1;i <= n; i++) { 16 scanf("%lld",&a[i].v); 17 a[i].xb = i; 18 } 19 while(!le.empty()) le.pop(); 20 while(!ri.empty()) ri.pop(); 21 } 22 23 void left() { 24 le.push(1); 25 for(int i = 2;i <= n; i++) { 26 if(le.empty()) { 27 le.push(i); 28 continue; 29 } 30 if(a[i].v >= a[le.top()].v) le.push(i); 31 if(a[i].v < a[le.top()].v) { 32 a[le.top()].r = i; 33 le.pop(); 34 while(true) { 35 if(le.empty()) break; 36 if(a[le.top()].v > a[i].v) { 37 a[le.top()].r = i; 38 le.pop(); 39 } 40 else break; 41 } 42 le.push(i); 43 } 44 } 45 le.pop(); 46 a[n].r = n + 1; 47 while(!le.empty()) { 48 a[le.top()].r = n + 1; 49 le.pop(); 50 } 51 } 52 53 void right() { 54 ri.push(a[n].xb); 55 for(int i = n - 1;i >= 1; i--) { 56 if(ri.empty()) { 57 ri.push(i); 58 continue; 59 } 60 if(a[i].v >= a[ri.top()].v) ri.push(i); 61 if(a[i].v < a[ri.top()].v) { 62 a[ri.top()].l = i; 63 ri.pop(); 64 while(true) { 65 if(ri.empty()) break; 66 if(a[ri.top()].v > a[i].v) { 67 a[ri.top()].l = i; 68 ri.pop(); 69 } 70 else break; 71 } 72 ri.push(i); 73 } 74 } 75 ri.pop(); 76 a[1].l = 0; 77 while(!ri.empty()) { 78 a[ri.top()].l = 0; 79 ri.pop(); 80 } 81 } 82 83 long long answer() { 84 long long ans = 0; 85 for(int i = 1;i <= n; i++) { 86 ans = max(ans,a[i].v * (a[i].r - a[i].l - 1)); 87 } 88 return ans; 89 } 90 91 void tiaoshi() { 92 for(int i = 1;i <= n; i++) 93 cout << i << " " << a[i].l << " " << a[i].r << " " << a[i].v << endl; 94 } 95 96 int main() { 97 while(true) { 98 scanf("%d",&n); 99 if(n == 0) return 0; 100 chushihua(); 101 left(); 102 right(); 103 printf("%lld\n",answer()); 104 } 105 return 0; 106 }
POJ 2559 Largest Rectangle in a Histogram(单调栈)
标签:lse rect nbsp iostream stream top his class 长度
原文地址:https://www.cnblogs.com/lipeiyi520/p/11237289.html