From 58b7e53508074d3a3db56b8b5c53618e77d417f6 Mon Sep 17 00:00:00 2001
From: YumYumNyang <khw121699@gmail.com>
Date: Wed, 20 Jul 2022 16:22:50 +0900
Subject: [PATCH] =?UTF-8?q?week02=20=EA=B3=BD=ED=98=9C=EC=9B=90?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../12.js"                                    | 57 +++++++++++++++++++
 .../5.js"                                     | 19 +++++++
 .../7.js"                                     | 17 ++++++
 3 files changed, 93 insertions(+)
 create mode 100644 "week02/week02-\352\263\275\355\230\234\354\233\220/12.js"
 create mode 100644 "week02/week02-\352\263\275\355\230\234\354\233\220/5.js"
 create mode 100644 "week02/week02-\352\263\275\355\230\234\354\233\220/7.js"

diff --git "a/week02/week02-\352\263\275\355\230\234\354\233\220/12.js" "b/week02/week02-\352\263\275\355\230\234\354\233\220/12.js"
new file mode 100644
index 0000000..15a5bf4
--- /dev/null
+++ "b/week02/week02-\352\263\275\355\230\234\354\233\220/12.js"
@@ -0,0 +1,57 @@
+const N = 8;
+
+function printSolution(board){
+    for(let i = 0; i < N; i++){
+        let str = ""
+        for(let j = 0; j < N; j++){
+            str += `${board[i][j]} `;
+        }
+        console.log(str);
+    }
+    console.log(" ");
+}
+
+
+function isSafe(board, row, col){
+    for(let i = 0; i < col; i++){
+        if(board[row][i] === 1){
+            return false;
+        }
+    }
+
+    for(i = row, j = col; i>=0 && j >=0; i--, j--){
+        if(board[i][j]){
+            return false;
+        }
+    }
+
+    for(i = row, j = col; j >= 0 && i < N; i++, j--){
+        if(board[i][j]){
+            return false;
+        }
+    }
+    return true; 
+}
+
+function solveNQUtil(board, col){
+    if(col >= N){
+        printSolution(board)
+        return true
+    }
+    let res = false;
+    for(let i = 0; i < N; i++){
+        if(isSafe(board, i, col) == true){
+            board[i][col] = 1
+            res = solveNQUtil(board, col+1) || res;
+            board[i][col] = 0
+        }
+    }
+    return res;
+}
+
+function solveNQ(){
+    let board = Array.from({length: N}, () => new Array(N).fill(0));
+    solveNQUtil(board, 0);
+    printSolution(board)
+}
+solveNQ()
\ No newline at end of file
diff --git "a/week02/week02-\352\263\275\355\230\234\354\233\220/5.js" "b/week02/week02-\352\263\275\355\230\234\354\233\220/5.js"
new file mode 100644
index 0000000..9402528
--- /dev/null
+++ "b/week02/week02-\352\263\275\355\230\234\354\233\220/5.js"
@@ -0,0 +1,19 @@
+function multiplyLinear(num, by){
+    if(by === 1) return num;
+    return num + multiplyLinear(num, by-1);
+}
+
+function multiplyLog(num, by){
+    if(by === 1) return num;
+
+    const res = multiplyLog(num, by/2);
+    if(by%2 === 0){
+        return res + res;
+    }else{
+        return res + res + num; 
+    }
+}
+
+const answer1 = multiplyLinear(5, 8);
+const answer2 = multiplyLog(5, 8);
+console.log(answer2);
\ No newline at end of file
diff --git "a/week02/week02-\352\263\275\355\230\234\354\233\220/7.js" "b/week02/week02-\352\263\275\355\230\234\354\233\220/7.js"
new file mode 100644
index 0000000..a7c8f3a
--- /dev/null
+++ "b/week02/week02-\352\263\275\355\230\234\354\233\220/7.js"
@@ -0,0 +1,17 @@
+let answer = new Set();
+
+function permutation(str, prefix){
+    if(str.length === 0){
+        answer.add(prefix);
+        return ;
+    }
+    for(let i = 0; i < str.length; i++){
+        let tmp = str.substring(0,i) + str.substring(i+1);
+        permutation(tmp, prefix+str[i]);
+    }
+    
+}
+
+permutation("abcdccc", "");
+
+Array.from(answer).forEach(str => console.log(str));
\ No newline at end of file