Jan 14, 2021 · Jan 31, 2021 · Jan 31, 2021 · Aug 10, 2021 · Aug 10, 2021 · Aug 10, 2021
diff --git a/README.md b/README.md
 | 319  |[Bulb Switcher](https://leetcode.com/problems/bulb-switcher/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_319.java)                                                                  |                                                                               |Medium| Brainteaser
 | 318  |[Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_318.java)                                                                  |                                                                               |Medium|
 | 317  |[Shortest Distance from All Buildings](https://leetcode.com/problems/shortest-distance-from-all-buildings/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_317.java)                                                                  |                                                                               |Hard|
 | 316  |[Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_316.java)                                                                  |                                                                               |Hard| Stack, Recursion, Greedy
 | 316  |[Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_316.java)                                                                  |                                                                               |Medium| Stack, Recursion, Greedy
 | 315  |[Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_315.java)                                                                  |                                                                               |Hard| Tree
 | 314  |[Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_314.java)                                                                  |                                                                               |Medium| HashMap, BFS
 | 313  |[Super Ugly Number](https://leetcode.com/problems/super-ugly-number/)| [Solution](../master/src/main/java/com/fishercoder/solutions/_313.java)                                                                  |                                                                               |Medium|
diff --git a/_1081.java b/_1081.java
 package com.fishercoder.solutions;

 import java.util.*;

 // same as 316. Remove Duplicate Letters
 // from https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_316.java

 public class _1002 {
    public class Solution1 {
        public String smallestSubsequence(String s) {
            int[] res = new int[26]; //will contain number of occurences of character (i+'a')
            boolean[] visited =
                    new boolean[26]; //will contain if character (i+'a') is present in current result Stack
                    char[] ch = s.toCharArray();
            for (char c : ch) {  //count number of occurences of character
                res[c - 'a']++;
            }
            Deque<Character> st = new ArrayDeque<>(); // answer stack
            int index;
            for (char c : ch) {
                index = c - 'a';
                res[index]--;   //decrement number of characters remaining in the string to be analysed
                if (visited[index]) {
                    //if character is already present in stack, dont bother
                    continue;
                }
                //if current character is smaller than last character in stack which occurs later in the string again
                //it can be removed and  added later e.g stack = bc remaining string abc then a can pop b and then c
                while (!st.isEmpty() && c < st.peek() && res[st.peek() - 'a'] != 0) {
                    visited[st.pop() - 'a'] = false;
                }
                st.push(c); //add current character and mark it as visited
                visited[index] = true;
            }

            StringBuilder sb = new StringBuilder();
            //pop character from stack and build answer string from back
            while (!st.isEmpty()) {
                sb.insert(0, st.pop());
            }
            return sb.toString();
        }
    }
 }
diff --git a/src/main/java/com/fishercoder/solutions/1961. Check If String Is a Prefix of Array.java b/src/main/java/com/fishercoder/solutions/1961. Check If String Is a Prefix of Array.java
 package com.fishercoder.solutions;

 public class _1961{
    public class Solution1 {
        public boolean isPrefixString(String s, String[] words) {

            String t="";
            int i=0;

            while(t.length()<s.length() && i<words.length){
                t+=words[i++];

                if(t.equals(s))
                    return true;
            }

            return false;

        }
    }
 }
diff --git a/src/main/java/com/fishercoder/solutions/_881.java b/src/main/java/com/fishercoder/solutions/_881.java
            return boats;
        }
    }

    public static class Solution2 {
        public int numRescueBoats(int[] people, int limit) {
            Arrays.sort(people);
            int end = people.length - 1;
            int start = 0;
            int boatcount = 0;
            while (end >= start) {
                if (people[end] == limit) {
                    end--;
                    boatcount++;
                } else if (people[end] + people[start] <= limit) {
                    start++;
                    end--;
                    boatcount++;
                } else {
                    end--;
                    boatcount++;
                }
            }
            return boatcount;
        }
    }

 }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1031,7 +1031,7 @@ _If you like this project, please leave me a star._ ★
		\| 319 \|[Bulb Switcher](https://leetcode.com/problems/bulb-switcher/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_319.java) \| \|Medium\| Brainteaser
		\| 318 \|[Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_318.java) \| \|Medium\|
		\| 317 \|[Shortest Distance from All Buildings](https://leetcode.com/problems/shortest-distance-from-all-buildings/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_317.java) \| \|Hard\|
		\| 316 \|[Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_316.java) \| \|Hard\| Stack, Recursion, Greedy
		\| 316 \|[Remove Duplicate Letters](https://leetcode.com/problems/remove-duplicate-letters/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_316.java) \| \|Medium\| Stack, Recursion, Greedy
		\| 315 \|[Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_315.java) \| \|Hard\| Tree
		\| 314 \|[Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_314.java) \| \|Medium\| HashMap, BFS
		\| 313 \|[Super Ugly Number](https://leetcode.com/problems/super-ugly-number/)\| [Solution](../master/src/main/java/com/fishercoder/solutions/_313.java) \| \|Medium\|
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,44 @@
		package com.fishercoder.solutions;

		import java.util.*;

		// same as 316. Remove Duplicate Letters
		// from https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_316.java

		public class _1002 {
		public class Solution1 {
		public String smallestSubsequence(String s) {
		int[] res = new int[26]; //will contain number of occurences of character (i+'a')
		boolean[] visited =
		new boolean[26]; //will contain if character (i+'a') is present in current result Stack
		char[] ch = s.toCharArray();
		for (char c : ch) { //count number of occurences of character
		res[c - 'a']++;
		}
		Deque<Character> st = new ArrayDeque<>(); // answer stack
		int index;
		for (char c : ch) {
		index = c - 'a';
		res[index]--; //decrement number of characters remaining in the string to be analysed
		if (visited[index]) {
		//if character is already present in stack, dont bother
		continue;
		}
		//if current character is smaller than last character in stack which occurs later in the string again
		//it can be removed and added later e.g stack = bc remaining string abc then a can pop b and then c
		while (!st.isEmpty() && c < st.peek() && res[st.peek() - 'a'] != 0) {
		visited[st.pop() - 'a'] = false;
		}
		st.push(c); //add current character and mark it as visited
		visited[index] = true;
		}

		StringBuilder sb = new StringBuilder();
		//pop character from stack and build answer string from back
		while (!st.isEmpty()) {
		sb.insert(0, st.pop());
		}
		return sb.toString();
		}
		}
		}
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,21 @@
		package com.fishercoder.solutions;

		public class _1961{
		public class Solution1 {
		public boolean isPrefixString(String s, String[] words) {

		String t="";
		int i=0;

		while(t.length()<s.length() && i<words.length){
		t+=words[i++];

		if(t.equals(s))
		return true;
		}

		return false;

		}
		}
		}
Original file line number	Diff line number	Diff line change
Expand Up		@@ -57,4 +57,28 @@ public int numRescueBoats(int[] people, int limit) {
		return boats;
		}
		}

		public static class Solution2 {
		public int numRescueBoats(int[] people, int limit) {
		Arrays.sort(people);
		int end = people.length - 1;
		int start = 0;
		int boatcount = 0;
		while (end >= start) {
		if (people[end] == limit) {
		end--;
		boatcount++;
		} else if (people[end] + people[start] <= limit) {
		start++;
		end--;
		boatcount++;
		} else {
		end--;
		boatcount++;
		}
		}
		return boatcount;
		}
		}

		}