Improved task 2732

src/main/java/g2701_2800/s2732_find_a_good_subset_of_the_matrix/Solution.java

@@ -1,50 +1,47 @@
 package g2701_2800.s2732_find_a_good_subset_of_the_matrix;
 
 // #Hard #Array #Greedy #Matrix #Bit_Manipulation
-// #2023_09_22_Time_7_ms_(70.65%)_Space_57.2_MB_(5.43%)
+// #2025_02_25_Time_2_ms_(100.00%)_Space_58.01_MB_(13.79%)
 
 import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.Arrays;
 import java.util.List;
-import java.util.Map;
 
 public class Solution {
+    private int[] arr = new int[32];
+
     public List<Integer> goodSubsetofBinaryMatrix(int[][] grid) {
-        int m = grid.length;
-        int n = grid[0].length;
-        if (m == 1 && sumArray(grid[0]) == 0) {
-            return List.of(0);
-        }
-        Map<Integer, Integer> pos = new HashMap<>();
-        for (int i = 0; i < m; i++) {
-            for (int mask = 0; mask < (1 << n); mask++) {
-                boolean valid = true;
-                for (int j = 0; j < n; j++) {
-                    if ((mask & (1 << j)) != 0 && grid[i][j] + 1 > 1) {
-                        valid = false;
-                        break;
-                    }
-                }
-                if (valid && pos.containsKey(mask)) {
-                    return List.of(pos.get(mask), i);
-                }
+        List<Integer> list = new ArrayList<>();
+        int n = grid.length;
+        Arrays.fill(arr, -1);
+        for (int i = 0; i < n; ++i) {
+            int j = get(grid[i]);
+            if (j == 0) {
+                list.add(i);
+                return list;
+            }
+            if (arr[j] != -1) {
+                list.add(arr[j]);
+                list.add(i);
+                return list;
             }
-            int curr = 0;
-            for (int j = 0; j < n; j++) {
-                if (grid[i][j] == 1) {
-                    curr = curr | (1 << j);
+            for (int k = 0; k < 32; ++k) {
+                if ((k & j) == 0) {
+                    arr[k] = i;
                 }
             }
-            pos.put(curr, i);
         }
-        return new ArrayList<>();
+        return list;
     }
 
-    private int sumArray(int[] arr) {
-        int sum = 0;
-        for (int num : arr) {
-            sum += num;
+    private int get(int[] nums) {
+        int n = nums.length;
+        int rs = 0;
+        for (int i = 0; i < n; ++i) {
+            if (nums[i] == 1) {
+                rs = (rs | (1 << i));
+            }
         }
-        return sum;
+        return rs;
     }
 }

src/main/java/g2701_2800/s2742_painting_the_walls/Solution.java

@@ -10,13 +10,11 @@ public int paintWalls(int[] cost, int[] time) {
         int[] dp = new int[n + 1];
         Arrays.fill(dp, (int) 1e9);
         dp[0] = 0;
-
         for (int i = 0; i < n; ++i) {
             for (int j = n; j > 0; --j) {
                 dp[j] = Math.min(dp[j], dp[Math.max(j - time[i] - 1, 0)] + cost[i]);
             }
         }
-
         return dp[n];
     }
 }