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Author: BrandonTang89

Other_Tasks/CF2069_A_Was_there_an_Array.py

@@ -0,0 +1,23 @@
+# cannot iff there is a subarray [1,0,1]
+# assign X to all 1s, and unique numbers to all 0s, the edges are easy
+for _ in range(int(input())):
+    n = int(input())
+    arr = list(map(int, input().split()))
+    
+    i = 0
+    prev = 0
+    seen1 = False
+    can = True
+    for i in range(n-2):
+        if arr[i] == 1: 
+            if prev == 1 and seen1:
+                can = False
+                break
+            
+            seen1 = True
+            prev = 0
+            continue
+        
+        prev += 1
+    
+    print("YES" if can else "NO")    

Other_Tasks/CF2069_B_Set_of_Stranger.cpp

@@ -0,0 +1,65 @@
+/**CF2069B
+ * For each colour, find out ifs doable in 1 or 2 moves (always doable in 2 moves via checkerboard style approach)
+ */
+#pragma GCC optimize("Ofast")
+#pragma GCC optimize("unroll-loops")
+#include <bits/stdc++.h>
+using namespace std;
+
+#define fast_cin()                    \
+    ios_base::sync_with_stdio(false); \
+    cin.tie(NULL);                    \
+    cout.tie(NULL);
+
+int dr[] = {-1, 1, 0, 0};
+int dc[] = {0, 0, -1, 1};
+
+int main() {
+    fast_cin();
+    int t;
+    cin >> t;
+    while (t--) {
+        int h, w;
+        cin >> h >> w;
+        vector<vector<int>> arr(h, vector<int>(w));
+        for (int i = 0; i < h; ++i) {
+            for (int j = 0; j < w; ++j) {
+                cin >> arr[i][j];
+            }
+        }
+
+        unordered_map<int, bool> d;
+
+        for (int r = 0; r < h; ++r) {
+            for (int c = 0; c < w; ++c) {
+                int colour = arr[r][c];
+                if (d[colour]) {
+                    continue;
+                }
+
+                for (int i = 0; i < 4; ++i) {
+                    int nr = r + dr[i];
+                    int nc = c + dc[i];
+
+                    if (nr >= 0 && nr < h && nc >= 0 && nc < w) {
+                        if (arr[nr][nc] == colour) {
+                            d[colour] = true;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+
+        vector<int> costs;
+        for (const auto& pair : d) {
+            costs.push_back(pair.second ? 2 : 1);
+        }
+
+        int total_cost = accumulate(costs.begin(), costs.end(), 0);
+        int max_cost = *max_element(costs.begin(), costs.end());
+        cout << total_cost - max_cost << endl;
+    }
+
+    return 0;
+}