CodeForces

题目链接：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <climits>
#include <cstring>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <map>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
using namespace std;#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define lowbit(x) (x & (-x))
#define CASET int _; scanf("%d", &_); for(int kase=1;kase<=_;kase++)typedef double db;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PII;static const int INF=0x3f3f3f3f;
static const ll INFL=0x3f3f3f3f3f3f3f3f;
static const db EPS=1e-10;
static const db PI=acos(-1.0);
static const int MOD=1e9+7;template <typename T>
inline void read(T &f) {f = 0; T fu = 1; char c = getchar();while (c < '0' || c > '9') { if (c == '-') { fu = -1; } c = getchar(); }while (c >= '0' && c <= '9') { f = (f << 3) + (f << 1) + (c & 15); c = getchar(); }f *= fu;
}
template <typename T>
void print(T x) {if (x < 0) putchar('-'), x = -x;if (x < 10) putchar(x + 48);else print(x / 10), putchar(x % 10 + 48);
}
static const int MAXN=1e5+10;
int n;
int a[MAXN],prefix[MAXN],suffix[MAXN];
multiset<int> ghs;
int main()
{read(n);for(int i=1;i<=n;i++){read(a[i]);prefix[i]=prefix[i-1]+a[i];}for(int i=n;i>=1;i--){suffix[i]=suffix[i+1]+a[i];ghs.insert(suffix[i]);}ghs.insert(0);int ans=prefix[n];for(int i=0;i<=n;i++){if(i) ghs.erase(ghs.find(suffix[i]));ans=max(ans,prefix[n]-2*prefix[i]-2*(*ghs.begin()));}printf("%d\n",ans);return 0;
}