diff --git a/src/problem1.js b/src/problem1.js
index 9a14f2c..799c7a5 100644
--- a/src/problem1.js
+++ b/src/problem1.js
@@ -1,6 +1,42 @@
 function problem1(pobi, crong) {
   var answer;
-  return answer;
+  var pobi_max, crong_max ;
+
+  if (pobi[0] % 2 == 0 || pobi[1] % 2 == 1 || crong[0] % 2 == 0 || crong[1] % 2 == 1 || pobi[1] - pobi[0] != 1 || crong[1] - crong[0] != 1) {
+    return -1;
+  }
+
+  pobi_1 = pobi[0].toString(); pobi_2 = pobi[1].toString();
+  crong_1 = crong[0].toString(); crong_2 = crong[1].toString();
+  pobi_max = Math.max(Math.max(plus(pobi_1), plus(pobi_2)), Math.max(multi(pobi_1), multi(pobi_2)))
+  crong_max = Math.max(Math.max(plus(crong_1), plus(crong_2)), Math.max(multi(crong_1), multi(crong_2)))
+
+  if (pobi_max > crong_max) {
+    return 1;
+  } else if (pobi_max < crong_max) {
+    return 2;
+  } else {
+    return 0;
+  }
+}
+
+function plus(now_num) {
+  var res = 0;
+
+  for (i = 0;i < now_num.length;i++) {
+    res += parseInt(now_num.substring(i, i + 1));
+  }
+  
+  return res;
 }
 
+function multi(now_num) {
+  var res = 1;
+
+  for (i = 0;i < now_num.length;i++) {
+    res *= parseInt(now_num.substring(i, i + 1));
+  }
+  
+  return res;
+}
 module.exports = problem1;
diff --git a/src/problem2.js b/src/problem2.js
index cebd07c..4e5e1b2 100644
--- a/src/problem2.js
+++ b/src/problem2.js
@@ -1,6 +1,22 @@
 function problem2(cryptogram) {
-  var answer;
-  return answer;
+  var pre_str = cryptogram ;
+  var now_str ;
+  while (1) {
+    now_str = search_str(pre_str)
+    if (now_str == pre_str || now_str.length == 0) {
+      return now_str ;
+    }
+    pre_str = now_str;
+  }
+}
+
+function search_str(now_str) {
+  for (var i = 0;i < now_str.length - 1;i++) {
+    if (now_str[i] == now_str[i + 1]) {
+      return now_str.slice(0, i) + now_str.slice(i + 2);
+    } 
+  }
+  return now_str;
 }
 
 module.exports = problem2;
diff --git a/src/problem3.js b/src/problem3.js
index 1baed28..597a038 100644
--- a/src/problem3.js
+++ b/src/problem3.js
@@ -1,6 +1,16 @@
 function problem3(number) {
-  var answer;
-  return answer;
+  var res = 0;
+  for (var i = 1;i <= number;i++) {
+    now_str = i.toString();
+    res += search_369(now_str, '3');
+    res += search_369(now_str, '6');
+    res += search_369(now_str, '9');
+  }
+  return res;
+}
+
+function search_369(str, num) {
+  return str.split(num).length - 1 ;
 }
 
 module.exports = problem3;
diff --git a/src/problem4.js b/src/problem4.js
index ee1d3bd..e033e2c 100644
--- a/src/problem4.js
+++ b/src/problem4.js
@@ -1,6 +1,19 @@
 function problem4(word) {
-  var answer;
-  return answer;
+  var res_str = '';
+  var now_ascii = 0;
+  for (i = 0;i < word.length;i++) {
+    if (word[i] == ' ') {
+      res_str += ' ';
+    } else {
+      now_ascii = word.charCodeAt(i);
+      if (now_ascii < 91) {
+        res_str += String.fromCharCode(90 - (now_ascii - 65));
+      } else {
+        res_str += String.fromCharCode(122 - (now_ascii - 97));
+      }
+    }
+  }
+  return res_str ;
 }
 
 module.exports = problem4;
diff --git a/src/problem5.js b/src/problem5.js
index 9368e87..3a1bbe9 100644
--- a/src/problem5.js
+++ b/src/problem5.js
@@ -1,6 +1,15 @@
 function problem5(money) {
-  var answer;
-  return answer;
+  var res_list = [0, 0, 0, 0, 0, 0, 0, 0, 0] ;
+  var money_list = {0 : 50000, 1 : 10000, 2 : 5000, 3 : 1000, 4 : 500, 5 : 100, 6 : 50, 7 : 10, 8 : 1} ;
+  var now_won = 0 ;
+
+  for (i = 0;i < 9;i++) {
+    now_won = money_list[i] ;
+    res_list[i] = Math.floor(money / now_won) ;
+    money %= now_won ;
+  }
+  
+  return res_list ;
 }
 
 module.exports = problem5;
diff --git a/src/problem6.js b/src/problem6.js
index 3f842b5..b329634 100644
--- a/src/problem6.js
+++ b/src/problem6.js
@@ -1,6 +1,33 @@
 function problem6(forms) {
-  var answer;
-  return answer;
+    var dupli_list = new Array(forms.length).fill(0) ;
+    var res_list = [] ;
+    for (var i = 0;i < forms.length;i++) {
+        for (var j = i + 1;j < forms.length;j++) {
+            if (dupli_search(forms[i][1], forms[j][1]) == true) {
+                if (dupli_list[i] == 0) {
+                    res_list.push(forms[i][0]);
+                    dupli_list[i] = 1;
+                }
+                if (dupli_list[j] == 0) {
+                    res_list.push(forms[j][0]);
+                    dupli_list[j] = 1;
+                }
+            }
+        }
+    }
+    res_list.sort()
+    return res_list;
+}
+
+function dupli_search(str1, str2) {
+    for (var i = 0;i < str1.length - 1;i++) {
+        for (var j = 0;j < str2.length - 1;j++) {
+            if (str1.slice(i, i + 2) == str2.slice(j, j + 2)) {
+                return true ;
+            }
+        }
+    }
+    return false ;
 }
 
 module.exports = problem6;
diff --git a/src/problem7.js b/src/problem7.js
index ee1bb9d..f590035 100644
--- a/src/problem7.js
+++ b/src/problem7.js
@@ -1,6 +1,53 @@
 function problem7(user, friends, visitors) {
-  var answer;
-  return answer;
+  let user_friends = [];
+  let score_dict = {};
+
+  for (let i = 0; i < friends.length; i++) {
+    let f0 = friends[i][0];
+    let f1 = friends[i][1];
+    if (f0 === user) {
+      user_friends.push(f1);
+    } else if (f1 === user) {
+      user_friends.push(f0);
+    }
+  }
+
+  for (let i = 0; i < friends.length; i++) {
+    let f0 = friends[i][0];
+    let f1 = friends[i][1];
+    if (f0 === user || f1 === user) {continue;}
+
+    if (user_friends.includes(f0)) {
+      if (score_dict[f1]) {
+        score_dict[f1] -= 10;
+      } else {
+        score_dict[f1] = -10;
+      }
+    } else if (user_friends.includes(f1)) {
+      if (score_dict[f0]) {
+        score_dict[f0] -= 10;
+      } else {
+        score_dict[f0] = -10;
+      }
+    }
+  }
+
+  for (let i = 0; i < visitors.length; i++) {
+    let now_visitors = visitors[i];
+    if (!user_friends.includes(now_visitors)) {
+      if (score_dict[now_visitors]) {
+        score_dict[now_visitors] -= 1;
+      } else {
+        score_dict[now_visitors] = -1;
+      }
+    }
+  }
+
+  let res_list = Object.entries(score_dict)
+    .sort((a, b) => a[1] - b[1])
+    .map(item => item[0]) ;
+
+  return res_list;
 }
 
 module.exports = problem7;