#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define double long double
inline int power(int a, int b) {
int x = 1;
while (b) {
if (b & 1) x *= a;
a *= a;
b >>= 1;
}
return x;
}
const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;
//_ ***************************** START Below *******************************
vector<int> a;
void consistency(int n) {
vector<int> prefixMax(n+1, 0);
vector<int> sufixMax(n+1, 0);
//* Kadane => P[R] = max(P[R-1] + a[R], a[R] , 0 )
//* curr = max(prev+a[i], a[i], 0)
int prev = 0;
int maxi = INT32_MIN;
for(int i=0; i<n; i++){
int curr = max(prev+a[i], a[i]);
curr = max(curr, 0LL);
prev = curr;
maxi = max(maxi, curr);
prefixMax[i] = maxi;
}
int next = 0;
maxi = INT32_MIN;
for(int i=n-1; i>=0; i--){
int curr = max(next+a[i], a[i]);
curr = max(curr, 0LL);
next = curr;
maxi = max(maxi, curr);
sufixMax[i] = maxi;
}
maxi = 0;
for(int i=0; i<n-1; i++){
maxi = max(maxi, prefixMax[i] + sufixMax[i+1]);
}
cout << maxi << endl;
}
void solve() {
a = {1, 5, -3, 4, -9,9, 2};
int n = a.size();
consistency(n) ;
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1;
while (t--) {
solve();
}
return 0;
}
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