leetcode

Author: ayoubzulfiqar

DeleteColumnsToMakeSorted/delete_columns_to_make_sorted.dart

@@ -0,0 +1,116 @@
+/*
+
+
+
+-* 944. Delete Columns to Make Sorted *-
+
+You are given an array of n strings strs, all of the same length.
+
+The strings can be arranged such that there is one on each line, making a grid. For example, strs = ["abc", "bce", "cae"] can be arranged as:
+
+abc
+bce
+cae
+You want to delete the columns that are not sorted lexicographically. In the above example (0-indexed), columns 0 ('a', 'b', 'c') and 2 ('c', 'e', 'e') are sorted while column 1 ('b', 'c', 'a') is not, so you would delete column 1.
+
+Return the number of columns that you will delete.
+
+ 
+
+Example 1:
+
+Input: strs = ["cba","daf","ghi"]
+Output: 1
+Explanation: The grid looks as follows:
+  cba
+  daf
+  ghi
+Columns 0 and 2 are sorted, but column 1 is not, so you only need to delete 1 column.
+Example 2:
+
+Input: strs = ["a","b"]
+Output: 0
+Explanation: The grid looks as follows:
+  a
+  b
+Column 0 is the only column and is sorted, so you will not delete any columns.
+Example 3:
+
+Input: strs = ["zyx","wvu","tsr"]
+Output: 3
+Explanation: The grid looks as follows:
+  zyx
+  wvu
+  tsr
+All 3 columns are not sorted, so you will delete all 3.
+ 
+
+Constraints:
+
+n == strs.length
+1 <= n <= 100
+1 <= strs[i].length <= 1000
+strs[i] consists of lowercase English letters.
+
+*/
+
+import 'dart:collection';
+
+class A {
+  int minDeletionSize(List<String> strs) {
+    int answer = 0;
+    for (int i = 0; i < strs[0].length; i++) {
+      for (int j = 0; j < strs.length - 1; j++) {
+        if (strs[j + 1].codeUnitAt(i) < strs[j].codeUnitAt(i)) {
+          answer++;
+          break;
+        }
+      }
+    }
+    return answer;
+  }
+}
+
+class B {
+  // O(n*m)
+  int minDeletionSize(List<String> strs) {
+    int deleted = 0;
+    if (strs.length == 0) return deleted;
+    int rowSize = strs[0].length;
+
+    for (int col = 0; col < rowSize; col++) {
+      if (!isSorted(strs, col)) deleted++;
+    }
+
+    return deleted;
+  }
+
+  bool isSorted(List<String> strs, int col) {
+    int N = strs.length;
+    int prev = 0;
+    for (int i = 0; i < N; i++) {
+      int c = strs[i].codeUnitAt(col);
+      //If out of order
+      if (c < prev) return false;
+      //update prev
+      prev = c;
+    }
+
+    return true; //In order the whole time
+  }
+}
+
+class C {
+  int minDeletionSize(List<String> strs) {
+    HashSet<int> hashSET = HashSet();
+    for (int j = 0; j < strs[0].length; j++) hashSET.add(j);
+    for (int i = 1; i < strs.length; i++) {
+      HashSet<int> tmp = HashSet();
+      tmp.addAll(hashSET);
+      for (int k in hashSET)
+        if (strs[i].codeUnitAt(k) < strs[i - 1].codeUnitAt(k)) tmp.remove(k);
+      hashSET = tmp;
+    }
+    return strs[0].length - hashSET.length;
+  }
+}

DeleteColumnsToMakeSorted/delete_columns_to_make_sorted.go

@@ -0,0 +1,74 @@
+package main
+
+// func minDeletionSize(strs []string) int {
+// 	var count int = 0
+// 	if len(strs) <= 1 {
+// 		return 0
+// 	}
+// 	for i := 0; i < len(strs[0]); i++ {
+// 		for j := 0; j < len(strs)-1; j++ {
+// 			if strs[j+1][i] < strs[j][i] {
+// 				count++
+// 				break
+// 			}
+// 		}
+// 	}
+// 	return count
+// }
+
+func minDeletionSize(strs []string) int {
+	var deleted int = 0
+	if len(strs) == 0 {
+		return deleted
+	}
+	var rowSize int = len(strs[0])
+	for col := 0; col < rowSize; col++ {
+		if !isSorted(strs, col) {
+			deleted++
+		}
+	}
+	return deleted
+}
+
+func isSorted(strs []string, col int) bool {
+	var size int = len(strs)
+	var previous byte = 0
+	for i := 0; i < size; i++ {
+		var c byte = strs[i][col]
+		if c < previous {
+			return false
+		}
+		previous = c
+
+	}
+	return true
+}
+
+/*
+
+  int minDeletionSize(List<String> strs) {
+    int deleted = 0;
+    if (strs.length == 0) return deleted;
+    int rowSize = strs[0].length;
+
+    for (int col = 0; col < rowSize; col++) {
+      if (!isSorted(strs, col)) deleted++;
+    }
+
+    return deleted;
+  }
+
+  bool isSorted(List<String> strs, int col) {
+    int N = strs.length;
+    int prev = 0;
+    for (int i = 0; i < N; i++) {
+      int c = strs[i].codeUnitAt(col);
+      //If out of order
+      if (c < prev) return false;
+      //update prev
+      prev = c;
+    }
+
+    return true; //In order the whole time
+  }
+*/

DeleteColumnsToMakeSorted/delete_columns_to_make_sorted.md

@@ -0,0 +1,73 @@
+# 🔥 3 Approaches 🔥 || Simple Fast and Easy || with Explanation
+
+## Solution - 1 BRUTE FORCE
+
+```dart
+class Solution {
+  int minDeletionSize(List<String> strs) {
+    int answer = 0;
+    for (int i = 0; i < strs[0].length; i++) {
+      for (int j = 0; j < strs.length - 1; j++) {
+        if (strs[j + 1].codeUnitAt(i) < strs[j].codeUnitAt(i)) {
+          answer++;
+          break;
+        }
+      }
+    }
+    return answer;
+  }
+}
+```
+
+## Solution - 2 O(n * m)
+
+```dart
+class Solution {
+  int minDeletionSize(List<String> strs) {
+    int deleted = 0;
+    if (strs.length == 0) return deleted;
+    int rowSize = strs[0].length;
+
+    for (int col = 0; col < rowSize; col++) {
+      if (!isSorted(strs, col)) deleted++;
+    }
+
+    return deleted;
+  }
+
+  bool isSorted(List<String> strs, int col) {
+    int N = strs.length;
+    int prev = 0;
+    for (int i = 0; i < N; i++) {
+      int c = strs[i].codeUnitAt(col);
+      //If out of order
+      if (c < prev) return false;
+      //update prev
+      prev = c;
+    }
+
+    return true; //In order the whole time
+  }
+}
+```
+
+## Solution - 3
+
+```dart
+import 'dart:collection';
+
+class Solution {
+  int minDeletionSize(List<String> strs) {
+    HashSet<int> hashSET = HashSet();
+    for (int j = 0; j < strs[0].length; j++) hashSET.add(j);
+    for (int i = 1; i < strs.length; i++) {
+      HashSet<int> tmp = HashSet();
+      tmp.addAll(hashSET);
+      for (int k in hashSET)
+        if (strs[i].codeUnitAt(k) < strs[i - 1].codeUnitAt(k)) tmp.remove(k);
+      hashSET = tmp;
+    }
+    return strs[0].length - hashSET.length;
+  }
+}
+```

README.md

@@ -175,6 +175,7 @@ This repo contain leetcode solution using DART and GO programming language. Most
 - [**886.** Possible Bipartition](PossibleBipartition/possible_bipartition.dart)
 - [**980.** Unique Paths III](UniquePathsIII/unique_paths_iii.dart)
 - [**520.** Detect Capital](DetectCapital/detect_capital.dart)
+- [**944.** Delete Columns to Make Sorted](DeleteColumnsToMakeSorted/delete_columns_to_make_sorted.dart)
 
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