sum of three values

CSES - CSES Problem Set/Sorting_And_Searching/Sum_of_Three_Values.cpp

@@ -0,0 +1,40 @@
+//  Sum of Three Values
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+//also possible with sorting
+
+
+int main() {
+    int n, x;
+    cin >> n >> x;
+    vector<int> array(n);
+    map<int, set<int>> map;
+    for (int i{}; i < n; i++) {
+        cin >> array[i];
+        map[array[i]].insert(i);
+    }
+
+    for (int i{}; i < n; i++) {
+        for (int j = i + 1; j < n; j++) {
+            int sum = x - array[i] - array[j];
+            if (map.count(sum)) {
+                bool first = map[sum].count(i);
+                bool second = map[sum].count(array[j]);
+                map[sum].erase(i);
+                map[sum].erase(j);
+                if (!map[sum].empty()) {
+                    cout << i + 1 <<  " " << j + 1 << " " << *map[sum].begin() + 1 << endl;
+                    return 0;
+                }
+                if (first) map[sum].insert(i);
+                if (second) map[sum].insert(j);
+            }
+        }
+    }
+
+    cout << "IMPOSSIBLE" << endl;
+    return 0;
+}