1 #include <cstdio> 2 #include <queue> 3 #include <cstring> 4 #include <iostream> 5 #include <algorithm> 6 #include <stack> 7 using namespace std; 8 9 typedef long long ll; 10 struct node{int v, id;}; 11 stack<node>q, sq; 12 13 int main(){ 14 int n; 15 scanf("%d", &n); 16 while(!sq.empty()) sq.pop(); 17 int ans = 0; 18 for(int i = 0;i < n;i++){ 19 int x; 20 scanf("%d", &x); 21 node a; 22 a.v = x; a.id = i; 23 if(sq.size() == 0 || sq.top().v > x){ 24 sq.push(a); 25 } 26 else{ 27 while(sq.top().v <= x){ 28 ans = max(ans, i - sq.top().id); 29 q.push(sq.top()); 30 sq.pop(); 31 if(sq.empty()) 32 break; 33 } 34 while(!q.empty()){ 35 sq.push(q.top()); 36 q.pop(); 37 } 38 } 39 } 40 printf("%d ", ans); 41 return 0; 42 }
后来提交一波的时候，最后一组数据超时，于是改用贪心，排序一遍过的：
1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 using namespace std; 5 6 const int maxn = 50000+5; 7 struct node{ 8 int id,v; 9 }a[maxn]; 10 11 bool cmp(node xx,node yy) 12 { 13 if (xx.v!=yy.v) 14 return xx.v<yy.v; 15 return xx.id<yy.id; 16 } 17 18 int main() 19 { 20 int n; 21 scanf("%d",&n); 22 for (int i=0;i<n;i++) 23 { 24 scanf("%d", &a[i].v); 25 a[i].id=i; 26 } 27 sort(a,a+n,cmp); 28 int ans = 0,Min=a[0].id; 29 for (int i=1;i<n;i++) 30 { 31 if (a[i].id > Min) 32 ans = max(ans, a[i].id-Min); 33 else Min = a[i].id; 34 } 35 printf("%d ",ans); 36 return 0; 37 }