Add Longest Substring with At Most One Flip Problem (#17)

xtenzQ · Jul 5, 2024 · c201cea · c201cea
1 parent 5393eb3
commit c201cea
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diff --git a/algorithms-and-data-structures/src/main/java/com/xtenzq/arrays/SlidingWindow.java b/algorithms-and-data-structures/src/main/java/com/xtenzq/arrays/SlidingWindow.java
@@ -23,4 +23,31 @@ public static int findLongestSubArraySumLessOrEqualK(int[] nums, int k) {
         }
         return answer;
     }
+
+    /**
+     * Finds the length of the longest substring of "1"s in a binary string after flipping at most one "0" to "1".
+     *
+     * @param s the binary string consisting of '0' and '1'
+     * @return the length of the longest substring achievable that contains only '1's after flipping at most one '0'
+     * @implNote This method runs in {@code O(n)} time complexity and {@code O(1)} space complexity,
+     * where {@code n} is the length of {@code s}.
+     */
+    public static int findLongestSubstringAfterOneFlip(String s) {
+        int left = 0, answer = 0, zeroCounter = 0;
+        for (int right = 0; right < s.length(); right++) {
+            if (s.charAt(right) == '0') {
+                zeroCounter++;
+            }
+
+            while (zeroCounter > 1) {
+                if (s.charAt(left) == '0') {
+                    zeroCounter--;
+                }
+                left++;
+            }
+
+            answer = Math.max(answer, right - left + 1);
+        }
+        return answer;
+    }
 }
diff --git a/algorithms-and-data-structures/src/test/java/com/xtenzq/arrays/SlidingWindowTest.java b/algorithms-and-data-structures/src/test/java/com/xtenzq/arrays/SlidingWindowTest.java
@@ -2,8 +2,9 @@
 
 import org.junit.jupiter.api.Test;
 
+import static com.xtenzq.arrays.SlidingWindow.findLongestSubstringAfterOneFlip;
 import static com.xtenzq.arrays.SlidingWindow.findLongestSubArraySumLessOrEqualK;
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class SlidingWindowTest {
 
@@ -48,4 +49,58 @@ void testFindLongestSubArraySumLessOrEqualK_EmptyArray() {
         int k = 5;
         assertEquals(0, findLongestSubArraySumLessOrEqualK(nums, k));
     }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_Example1() {
+        String s = "1101100111";
+        assertEquals(5, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_AllOnes() {
+        String s = "1111111";
+        assertEquals(7, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_AllZeros() {
+        String s = "00000";
+        assertEquals(1, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_SingleZero() {
+        String s = "1";
+        assertEquals(1, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestOneBinaryString_SingleSubstringAfterOne() {
+        String s = "0";
+        assertEquals(1, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_AlternateOnesAndZeros() {
+        String s = "1010101010";
+        assertEquals(3, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_LeadingZeros() {
+        String s = "000011110000";
+        assertEquals(5, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_TrailingZeros() {
+        String s = "11110000";
+        assertEquals(5, findLongestSubstringAfterOneFlip(s));
+    }
+
+    @Test
+    void testFindLongestSubstringAfterOneFlip_ComplexPattern() {
+        String s = "100110111001111";
+        assertEquals(6, findLongestSubstringAfterOneFlip(s));
+    }
 }