feat: 우체국 추가

src/main/kotlin/hyunsoo/54week/우체국.kt

@@ -0,0 +1,53 @@
+package hyunsoo.`54week`
+
+/**
+ *
+ * <문제>
+ * [우체국](https://www.acmicpc.net/problem/2141)
+ *
+ * - 아이디어
+ *
+ * - 트러블 슈팅
+ *
+ */
+class `전현수_우체국` {
+
+    private data class VillageInfo(val villageNum: Long, val peopleCnt: Long)
+
+    private val villageInfoList = mutableListOf<VillageInfo>()
+
+    fun solution() {
+
+        var totalPeopleCnt = 0L
+        var prefixSumOfPeopleCnt = 0L
+        val n = readln().toInt()
+
+        repeat(n) {
+
+            val (villageNum, peopleCnt) = readln().split(" ").map { it.toLong() }
+            villageInfoList.add(VillageInfo(villageNum, peopleCnt))
+            totalPeopleCnt += peopleCnt
+
+        }
+
+        val mid = if (totalPeopleCnt % 2 == 0L) totalPeopleCnt / 2 else totalPeopleCnt / 2 + 1
+
+        villageInfoList
+            .sortedBy { it.villageNum }
+            .forEach {
+
+                val (vil, curPeopleCnt) = it
+
+                prefixSumOfPeopleCnt += curPeopleCnt
+
+                if (mid <= prefixSumOfPeopleCnt) {
+                    println(vil)
+                    return
+                }
+            }
+    }
+}
+
+fun main() {
+    전현수_우체국().solution()
+}