From ef76ee6f9c953f6742f7b55e2775686adedb6bfb Mon Sep 17 00:00:00 2001
From: tahir <chaudharitahir1@gmail.com>
Date: Sat, 21 Oct 2023 20:09:03 +0530
Subject: [PATCH] 80th problem

---
 71-80/77. Combinations.js                     | 14 ++++++++++
 71-80/78. Subsets.js                          | 13 ++++++++++
 71-80/79. Word Search.js                      | 26 +++++++++++++++++++
 ... Remove Duplicates from Sorted Array II.js | 18 +++++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 71-80/77. Combinations.js
 create mode 100644 71-80/78. Subsets.js
 create mode 100644 71-80/79. Word Search.js
 create mode 100644 71-80/80. Remove Duplicates from Sorted Array II.js

diff --git a/71-80/77. Combinations.js b/71-80/77. Combinations.js
new file mode 100644
index 0000000..47fa21f
--- /dev/null
+++ b/71-80/77. Combinations.js	
@@ -0,0 +1,14 @@
+var combine = function(n, k) {
+  let result = []
+  let traverse = (arr, depth) =>{
+    if (arr.length === k) {
+      result.push(arr)
+      return
+    }
+    if (depth > n) {return}
+    traverse(arr, depth + 1)
+    traverse(arr.concat(depth), depth + 1)
+  }
+  traverse([], 1)
+  return result;
+};
\ No newline at end of file
diff --git a/71-80/78. Subsets.js b/71-80/78. Subsets.js
new file mode 100644
index 0000000..882eeee
--- /dev/null
+++ b/71-80/78. Subsets.js	
@@ -0,0 +1,13 @@
+var subsets = function(nums) {
+    let ans = [[]]
+    let k = []
+    for(let i = 0 ; i < nums.length ; i++){
+        let n = ans.length
+        for(let j = 0 ; j < n ;j++){
+            k = Array.from(ans[j])
+            k.push(nums[i])
+            ans.push(k)
+        }
+    }
+    return ans
+};
\ No newline at end of file
diff --git a/71-80/79. Word Search.js b/71-80/79. Word Search.js
new file mode 100644
index 0000000..ceec009
--- /dev/null
+++ b/71-80/79. Word Search.js	
@@ -0,0 +1,26 @@
+var exist = function(board, word) {
+     let found = false;
+  const backtrack = (board, rIdx, cIdx, word, letterIdx) => {
+    if(rIdx >= 0 && rIdx < board.length && cIdx >=0 && cIdx < board[0].length && board[rIdx][cIdx] === word[letterIdx]) {
+      if(letterIdx === word.length-1) found ||= true;
+      const curLetter = word[letterIdx];
+      board[rIdx][cIdx] = '';
+      backtrack(board, rIdx+1, cIdx, word, letterIdx+1);
+      backtrack(board, rIdx-1, cIdx, word, letterIdx+1);
+      backtrack(board, rIdx, cIdx+1, word, letterIdx+1);
+      backtrack(board, rIdx, cIdx-1, word, letterIdx+1);
+      board[rIdx][cIdx] = curLetter;
+    }
+  };
+
+  let letterIdx = 0;
+  board.forEach((row, rIdx) => {
+    row.forEach((cell, cIdx) => {
+      if(cell === word[letterIdx]) {
+        backtrack(board, rIdx, cIdx, word, letterIdx);
+        if(found) return found;
+      }
+    })
+  });  
+  return found;
+}
\ No newline at end of file
diff --git a/71-80/80. Remove Duplicates from Sorted Array II.js b/71-80/80. Remove Duplicates from Sorted Array II.js
new file mode 100644
index 0000000..3923076
--- /dev/null
+++ b/71-80/80. Remove Duplicates from Sorted Array II.js	
@@ -0,0 +1,18 @@
+var removeDuplicates = function(nums) {
+    let j = 0
+    let [m,c,k] = [0,0,0]
+    for(let i = 0 ; i <nums.length ;i++){
+        k = nums[i]
+        c = 0
+        while(nums[i] == k){
+            if(c < 2){
+                nums[j++] = k
+                c++
+                m++
+            }
+            i++
+        }
+        i--
+    }
+    nums.length = m
+};
\ No newline at end of file