Codeforces Round #FF (Div. 1) A. DZY Loves Sequences

题目链接：

http://www.codeforces.com/contest/446/problem/A

题解:

dp1[x]表示以x结尾的最大严格升序连续串，dp2[x]表示以x开头的最大严格升序连续串

#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
#include<list>
#include<stack>
#include<algorithm>
using namespace std;

const int maxn =  + ;
const int INF = 2e9;
typedef __int64 LL;

int n;
int dp1[maxn], dp2[maxn];
int arr[maxn];

void init() {
    memset(dp1, , sizeof(dp1));
    memset(dp2, , sizeof(dp2));
}

int main() {
    while (scanf("%d", &n) ==  && n) {
        init();
        for (int i = ; i < n; i++) scanf("%d", arr + i);
        dp1[] = ;
        for (int i = ; i < n; i++) {
            if (arr[i] > arr[i - ]) dp1[i] = dp1[i - ] + ;
            else dp1[i] = ;
        }
        dp2[n - ] = ;
        for (int i = n - ; i >= ; i--) {
            if (arr[i] < arr[i + ]) dp2[i] = dp2[i + ] + ;
            else dp2[i] = ;
        }
        int ans = max(dp2[] + , dp1[n - ]+);
        for (int i = ; i < n - ; i++) {
            if (arr[i - ] < arr[i + ] - ) ans = max(ans, dp1[i - ] +  + dp2[i + ]);
            else {
                ans = max(ans,dp1[i - ] + );
                ans = max(ans,dp2[i + ] + );
            }
        }
        printf("%d\n", ans);
    }
    return ;
}