例题8-8　防线（Defense Lines, ACM/ICPC CERC 2010, UVa1471）

#include <set>
#include <map>
#include <ctime>
#include <cmath>
#include <stack>
#include <queue>
#include <deque>
#include <cstdio>
#include <string>
#include <vector>
#include <cctype>
#include <sstream>
#include <utility>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#define SF(a) scanf("%d", &a)
#define PF(a) printf("%d\n", a)
#define SFF(a, b) scanf("%d%d", &a, &b)
#define SFFF(a, b, c) scanf("%d%d%d", &a, &b, &c)
#define SFFFF(a, b, c, d) scanf("%d%d%d%d", &a, &b, &c, &d)
#define CLEAR(a, b) memset(a, b, sizeof(a))
#define IN() freopen("in.txt", "r", stdin)
#define OUT() freopen("out.txt", "w", stdout)
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define LL long long
#define maxn 200005
#define maxm 205
#define mod 1000000007
#define INF 10000007
#define eps 1e-4
using namespace std;
int buf[20], l;
int read() {
int x = 0; char ch = getchar(); bool f = 0;
while (ch < '0' || ch > '9') { if (ch == '-') f = 1; ch = getchar(); }
while (ch >= '0' && ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
return f ? -x : x;
}
void write(int x) {
if (!x) { putchar(48); return; }
l = 0; if (x < 0) putchar('-'), x = -x;
while (x) buf[++l] = x % 10, x = x / 10;
while (l) putchar(buf[l--] + 48);
}
//-------------------------CHC------------------------------//
struct Node {
int a, g;
Node(int a, int g ): a(a), g(g) { }
bool operator<(const Node &rhs) const { return a < rhs.a; }
};
set<Node> s;
int a[maxn], g[maxn], f[maxn];

int main() {
int T;
T = read();
while (T--) {
s.clear();
int n;
n = read();
FOR(i, 0, n) a[i] = read();
g[0] = 1;
FOR(i, 1, n) {
if (a[i] > a[i - 1]) g[i] = g[i - 1] + 1;
else g[i] = 1;
}
f[n - 1] = 1;
for (int i = n - 2; i >= 0; --i) {
if (a[i] < a[i + 1]) f[i] = f[i + 1] + 1;
else f[i] = 1;
}
int ans = 1;
s.insert(Node(a[0], g[0]));
FOR(i, 1, n) {
Node cur(a[i], g[i]);
set<Node>::iterator it = s.lower_bound(cur);
bool ok = true;
if (it != s.begin()) {
if (it != s.end() && it->a == cur.a && it->g >= cur.g) ok = false;
ans = max(ans, f[i] + (--it)->g);
if (it->g >= cur.g) ok = false;
}
if (ok) {
s.erase(cur);
s.insert(cur);
it = s.upper_bound(cur);
while (it != s.end() && it->g <= cur.g) s.erase(it++);
}
}
write(ans); puts("");
}
return 0;
}