diff --git a/typing.c b/typing.c
index c9b228b..ea59af6 100644
--- a/typing.c
+++ b/typing.c
@@ -3,17 +3,76 @@
 #include <string.h>
 #include <time.h>
 
+#define MAX_LEN 10000 /* 対応できる文字列の長さの上限 */
+
+void swap_pointers(int **p2p1, int **p2p2) {
+    /* ２つのポインタが指すアドレスを交換する */
+    int *temp = *p2p1;
+    *p2p1 = *p2p2;
+    *p2p2 = temp;
+}
+
+int lowest(int values[], int n) { /* 整数の配列の中から最小値を返す */
+    int lowest = values[0];
+    int i = 0;
+    for (i = 1; i < n; i++) {
+        if (values[i] < lowest) {
+            lowest = values[i];
+        }
+    }
+    return lowest;
+}
+
+int eddist_iter(char *str1, char *str2, int len1, int len2) {
+    /* （再帰呼び出しを使わずに）編集距離（レーベンシュタイン距離）を計算する関数
+    str1, str2 は対象の文字列
+    len1, len2 は文字列の長さ */
+    int row1[MAX_LEN+1] = {0};
+    int row2[MAX_LEN+1] = {0};
+    int *prev = row1; /* 直前の行 */
+    int *current = row2; /* 今見ている行 */
+    int i, j;
+    int opt[3];
+
+    for (i = 0; i <= len1; i++) {
+        for (j = 0; j <= len2; j++) {
+            /* str1の終端に到達した場合、str2の残りの文字数を返す */
+            if (i == 0) {
+                current[j] = j;
+            /* str2の終端に到達した場合、str1の残りの文字数を返す */
+            } else if (j == 0) {
+                current[j] = i;
+            /* 両方の文字列が対象の位置に同じ文字を持つ場合、編集距離は増えない */
+            } else if (str1[i-1] == str2[j-1]) {
+                current[j] = prev[j-1];
+            /* 対象の位置にある文字が異なる場合、可能な編集を全て検討し
+            最小値を求める */
+            } else {
+                opt[0] = current[j-1]; /* str1に1文字を挿入することと同じ */
+                opt[1] = prev[j]; /* str1から1文字を削除することと同じ */
+                opt[2] = prev[j-1]; /* str1の1文字を置き換えることと同じ */
+                current[j] = 1 + lowest(opt, 3);
+            }
+        }
+        swap_pointers(&prev, &current); /* 今回調べた行（current）が今度 prev になる */
+    }
+    /* 処理が終わったら prev の最後の要素に最小距離が入っているのでそれを返す */
+    return prev[len2];
+}
+
+
+
 int main() {
   
   char *lv1[] = {"anthem", "addicted", "crazy", "cassette", "curtain", "double", "everlasting", "gangster", "hoodstar", "hysteria", "imitation", "interlude", "lemonade", "louder", "legend", "navigator", "ordinary", "papercut", "perfect", "rollin", "rosy", "special", "strawberry", "telephone", "uncrushable"};
 
-  char *lv2[] = {"Life_is_not_fair", "Whenever_You_Call", "No_matter_the_time", "There's_nothing_in_this_world", "I_never_said_it_would_be_easy", "I'm_still_writing_all_this_love_for_you", "I_don't_know_what_I_have_done_to_you", "Cause_you_don't_wanna_talk", "But_it's_so_hard_to_tell_you_with_my_words", "Keep_going_my_way", "Just_do_it_Believe_yourself"};
+  char *lv2[] = {"Life_is_not_fair", "Whenever_you_call", "No_matter_the_time", "There's_nothing_in_this_world", "I_never_said_it_would_be_easy", "I'm_still_writing_all_this_love_for_you", "I_don't_know_what_I_have_done_to_you", "Cause_you_don't_wanna_talk", "But_it's_so_hard_to_tell_you_with_my_words", "Keep_going_my_way", "Just_do_it_believe_yourself"};
 
-  char *lv3[] = {"The_odds_are_against_me._But_here_to_win_it._Oh_girl,_I'm_all_in_for_you._I_can't_stop_thinking_'bout_you._Can't_hide_it._Baby,_come_all_in_for_me.", "Girl,_you_slay_the_night_away._Put_me_in_a_daze._But_you're_with_another_man.", "Everyday_I_wake_up,_See_the_world_that's_brand_new._Some_places_I_can_never_go_back_for_good.", "Right,_Nothing_lasts_forever,_Yeah,_Nothing_but_our_love._I_wanna_build_a_brighter_future_for_the_world_to_come.", "Every_single_day,_The_world_just_keeps_on_changing._And_I_pray_that_we're_headed_for_the_happy_ending."};
+  char *lv3[] = {"The_odds_are_against_me._But_here_to_win_it._Oh_girl,_I'm_all_in_for_you._I_can't_stop_thinking_about_you._Can't_hide_it._Baby,_come_all_in_for_me.", "Girl,_you_slay_the_night_away._Put_me_in_a_daze._But_you're_with_another_man.", "Everyday_I_wake_up,_See_the_world_that's_brand_new._Some_places_I_can_never_go_back_for_good.", "Right,_Nothing_lasts_forever,_Yeah,_Nothing_but_our_love._I_wanna_build_a_brighter_future_for_the_world_to_come.", "Every_single_day,_The_world_just_keeps_on_changing._And_I_pray_that_we're_headed_for_the_happy_ending."};
 
   char line[100];
   char answer[100];
-  int i, rv, level;
+  int i, rv, level, dist, sum=0;
   time_t start = time(0);
   srand(start);
 
@@ -36,29 +95,41 @@
       while(1) {
 	printf("第%d問: %s\n", i+1, lv1[rv]);
 	scanf("%s", answer);
+	printf("\n");
+	dist = eddist_iter(lv1[rv], answer, strlen(lv1[rv]), strlen(answer));
+        sum += dist;
 	break;
       }
     }
+    printf("編集距離: %d\n", sum);
     break;
   case 2:
     for (i=0; i<5; i++) {
       rv = rand() % 11;
       while(1) {
-      printf("第%d問: %s\n", i+1, lv2[rv]);
-      scanf("%s", answer);
-      break;
+	printf("第%d問: %s\n", i+1, lv2[rv]);
+	scanf("%s", answer);
+	printf("\n");
+	dist = eddist_iter(lv2[rv], answer, strlen(lv2[rv]), strlen(answer));
+	sum += dist;
+	break;
       }
     }
+    printf("編集距離: %d\n", sum);
     break;
   case 3:
     for (i=0; i<3; i++) {
       rv = rand() % 5;
       while(1) {
-      printf("第%d問: %s\n", i+1, lv3[rv]);
-      scanf("%s", answer);
-      break;
+	printf("第%d問: %s\n", i+1, lv3[rv]);
+	scanf("%s", answer);
+	printf("\n");
+	dist = eddist_iter(lv3[rv], answer, strlen(lv3[rv]), strlen(answer));
+	sum += dist;
+	break;
       }
     }
+    printf("編集距離: %d\n", sum);
     break;
   }
   printf("時間は %d 秒でした!\n", time(0)-start);