2019-5-22训练
http://codeforces.com/problemset/problem/1155/D
1 #include<iostream> 2 #include<cstdio> 3 #include<cmath> 4 #include<algorithm> 5 #include<string> 6 using namespace std; 7 typedef long long ll; 8 const int maxn = 500100; 9 ll dp[maxn][3]; 10 ll n, x; 11 ll a[maxn]; 12 ll ans; 13 int main() 14 { 15 cin >> n >> x; 16 for (int i = 1; i <= n; i++) 17 { 18 cin >> a[i]; 19 } 20 dp[0][0] = 0;//之前不选的最大 21 dp[0][1] = 0;//选这个最大 22 dp[0][2] = 0;//现在以后不选的最大 23 for(int i = 1; i <= n; i++) 24 { 25 dp[i][0] = max(dp[i - 1][0] + a[i], a[i]); 26 27 dp[i][1] = max(dp[i - 1][1] + a[i] * x, dp[i - 1][0] + a[i] * x); 28 dp[i][1] = max(dp[i][1], a[i] * x); 29 30 dp[i][2] = max(dp[i - 1][2] + a[i], dp[i - 1][1] + a[i]); 31 dp[i][2] = max(dp[i][2], a[i]); 32 33 ans = max(ans, dp[i][0]); 34 ans = max(ans, dp[i][1]); 35 ans = max(ans, dp[i][2]); 36 } 37 printf("%lld\n", ans); 38 return 0; 39 }
