AKASH-ALAM · November 16, 2022 16:35 · Nov 16, 2022
diff --git a/Array Negations.cpp b/Array Negations.cpp
@@ -0,0 +1,84 @@
+/**
+ *  Author  : Pnictogen
+ *  Task    :
+ *  Algo    :
+**/
+#include <bits/stdc++.h>
+
+#define endl          '\n'
+#define sqr(x)        (x) * (x)
+#define gcd(x,y)      __gcd(x,y)
+#define lcm(x,y)      ((x/gcd(x,y)) * y)
+#define sz(x)         (int)x.size()
+#define all(x)        (x).begin(),(x).end()
+#define rall(x)       (x).rbegin(),(x).rend()
+#define prec(x)       fixed<<setprecision(x)
+#define min3(a,b,c)   min(a,min(b,c))
+#define max3(a,b,c)   max(a,max(b,c))
+#define min4(a,b,c,d) min(a,min(b,min(c,d)))
+#define max4(a,b,c,d) max(a,max(b,max(c,d)))
+#define unsyncIO      ios_base::sync_with_stdio(false); cin.tie(nullptr)
+
+using namespace std;
+using ll = long long;
+using db = double;
+using ld = long double;
+using ull = unsigned long long;
+
+const ld PI = acos((ld) - 1);
+const int MOD = 1e9 + 7;
+const ll INF = 2e18 + 1;
+const ld EPS = 1e-9;
+const int MX = 2e5;
+
+#ifdef LOCAL
+#include"debug.h"
+#else
+#define debug(...)
+#endif
+// Note : Each element in the array can be negated multiple times.
+void solve() {
+	int n, k, pos = 0;	cin >> n >> k;
+	vector <int> v(n);
+	for (int i = 0; i < n; i++) cin >> v[i];
+	sort(v.begin(), v.end());
+	ll sum = 0;
+	for (int i = 0; i < k; i++) {
+		if (v[i] <= 0) {
+			v[i] = -v[i];
+			pos++; // count how many negatiove we made positive
+		} else break;
+	}
+	k = (k - pos) % 2; // if we negation twice of a element it remains same.
+	if (k == 1) {// if k is 1 then we make the smallest negation so that the sum is max
+		sort(v.begin(), v.end());
+		v[0] = -v[0];
+	}
+
+	sum = accumulate(v.begin(), v.end(), 0ll);
+	/*for (int data : v) cout << data << " ";
+	cout << endl;*/
+	cout << sum << endl;
+
+}
+
+int main() {
+
+#ifdef LOCAL
+	clock_t tStart = clock();
+	freopen("in.txt", "r", stdin);
+	freopen("out.txt", "w", stdout);
+#endif
+	unsyncIO;
+
+	int t = 1;	cin >> t;
+
+	while (t--) {
+		solve();
+	}
+
+#ifdef LOCAL
+	cerr << "\nRuntime: " << (ld) (clock() - tStart) / CLOCKS_PER_SEC << " Seconds" << endl;
+#endif
+	return 0;
+}