hdu 5328 Problem Killer

求最长的等比或者等差数列

扫两遍数组分别统计就行了

#include <bits/stdc++.h>#include <map>#include <set>#include <queue>#include <stack>#include <cmath>#include <time.h>#include <vector>#include <cstdio>#include <string>#include <iomanip>///cout << fixed << setprecision(13) << (double) x << endl;#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>using namespace std;#define lson l, mid, rt << 1#define rson mid + 1, r, rt << 1 | 1#define ls rt << 1#define rs rt << 1 | 1#define pi acos(-1.0)#define eps 1e-8#define Mp(a, b) make_pair(a, b)#define asd puts("asdasdasdasdasdf");typedef long long ll;//typedef __int64 LL;const int inf = 0x3f3f3f3f;ll a[1000010];int main(){int tot, n;scanf("%d", &tot);while( tot-- ) {scanf("%d", &n);for( int i = 1; i <= n; ++i ) scanf("%lld", &a[i]);if( n <= 2 ) {printf("%d\n", n);continue;}int ans = 2, tmp = 1;for( int i = 2; i < n; ++i ) {if( a[i] * 2 == a[i-1] + a[i+1] ) {ans = max( ans, i+2 - tmp );}else {tmp = i;}}tmp = 1;for( int i = 2; i < n; ++i ) {if( a[i] * a[i] == a[i-1] * a[i+1] ) {ans = max( ans, i+2 - tmp );}else {tmp = i;}}printf("%d\n", ans);}return 0;}