这个是动态的，所以要用线段树维护。代码里有注释因为ls敲成lsum，rs敲成rsum查错查了好久。。
1 #include <set> 2 #include <map> 3 #include <cmath> 4 #include <ctime> 5 #include <queue> 6 #include <stack> 7 #include <cctype> 8 #include <cstdio> 9 #include <string> 10 #include <vector> 11 #include <cstdlib> 12 #include <cstring> 13 #include <iostream> 14 #include <algorithm> 15 using namespace std; 16 typedef unsigned long long ull; 17 typedef long long ll; 18 const int inf = 0x3f3f3f3f; 19 const double eps = 1e-8; 20 template <class T> 21 inline bool scan_d(T &ret) 22 { 23 char c; 24 int sgn; 25 if(c=getchar(),c==EOF) return 0; 26 while(c!='-'&&(c<'0'||c>'9')) 27 c=getchar(); 28 sgn=(c=='-')?-1:1; 29 ret=(c=='-')?0:(c-'0'); 30 while(c=getchar(),c>='0'&&c<='9') 31 ret=ret*10+(c-'0'); 32 ret*=sgn; 33 return 1; 34 } 35 36 const int maxn = 1e5+10; 37 int ls[maxn<<2],rs[maxn<<2]; //ls为区间左值，rs为区间右值 比较时要用到。 38 int lsum[maxn<<2],rsum[maxn<<2],sum[maxn<<2]; //lsum为区间左上升长度，rsum为区间右上升长度，sum为区间最大上升长度。 39 40 void push_up(int l,int r,int pos) 41 { 42 ls[pos] = ls[pos<<1]; 43 rs[pos] = rs[pos<<1|1]; 44 lsum[pos] = lsum[pos<<1]; 45 rsum[pos] = rsum[pos<<1|1]; 46 sum[pos] = max(sum[pos<<1],sum[pos<<1|1]); 47 int mid = (l + r) >> 1; 48 if (ls[pos<<1|1] > rs[pos<<1]) 49 { 50 sum[pos] = max(sum[pos],rsum[pos<<1] + lsum[pos<<1|1]); 51 if (lsum[pos<<1] == mid - l + 1) //左区间左上升长度已满 52 lsum[pos] += lsum[pos<<1|1]; 53 if (rsum[pos<<1|1] == r - mid) //同理， 54 rsum[pos] += rsum[pos<<1]; 55 } 56 } 57 58 void build (int l,int r,int pos) 59 { 60 if (l == r) 61 { 62 int tmp; 63 scanf ("%d",&tmp); 64 ls[pos] = tmp; 65 rs[pos] = tmp; 66 lsum[pos] = rsum[pos] = sum[pos] = 1; 67 return; 68 } 69 int mid =(l + r) >> 1; 70 build(l,mid,pos<<1); 71 build(mid+1,r,pos<<1|1); 72 push_up(l,r,pos); 73 } 74 75 void update(int l,int r,int pos,int x,int val) 76 { 77 if (l == r) 78 { 79 ls[pos] = rs[pos] = val; 80 return; 81 } 82 int mid = (l + r) >> 1; 83 if (x <= mid) 84 update(l,mid,pos<<1,x,val); 85 else 86 update(mid+1,r,pos<<1|1,x,val); 87 push_up(l,r,pos); 88 } 89 90 91 int query(int l,int r,int pos,int ua,int ub) 92 { 93 if (ua <= l && ub >= r) 94 { 95 return sum[pos]; 96 } 97 int mid = (l + r) >> 1; 98 int ans1 = 0,ans2 = 0,ans3 = 0; 99 if (ua <= mid) 100 ans1 = query(l,mid,pos<<1,ua,ub); 101 if (ub > mid) 102 ans2 = query(mid+1,r,pos<<1|1,ua,ub); 103 if (ls[pos<<1|1] > rs[pos<<1]) 104 ans3 = min(lsum[pos<<1|1],ub-mid) + min(rsum[pos<<1],mid-ua+1); 105 return max(ans1,max(ans2,ans3)); 106 } 107 108 109 int main(void) 110 { 111 #ifndef ONLINE_JUDGE 112 freopen("in.txt","r",stdin); 113 #endif 114 int t; 115 cin>>t; 116 while (t--) 117 { 118 int n,q; 119 scanf ("%d%d",&n,&q); 120 build(1,n,1); 121 char op[10]; 122 int x,y; 123 for (int i = 0; i < q; i++) 124 { 125 scanf ("%s%d%d",op,&x,&y); 126 if (op[0] == 'Q') 127 printf("%d ",query(1,n,1,x+1,y+1)); 128 if (op[0] == 'U') 129 update(1,n,1,x+1,y); 130 } 131 } 132 return 0; 133 }