动态数组

src/main/java/com/code/leet/entiy/LCArray.java

@@ -0,0 +1,39 @@
+package com.code.leet.entiy;
+
+import java.util.stream.IntStream;
+
+public class LCArray {
+
+    int[] arr;
+    int curIndex;
+    int maxSize;
+
+    public LCArray() {
+        arr = new int[1];
+        curIndex = 0;
+        maxSize = 1;
+    }
+
+    public void push_back(int n) {
+        if(curIndex==maxSize){
+            maxSize *= 2;
+            int[] temp = new int[maxSize];
+            if (curIndex >= 0) System.arraycopy(arr, 0, temp, 0, curIndex);
+            arr = temp;
+        }
+        arr[curIndex] = n;
+        curIndex++;
+    }
+
+    public void pop_back() {
+        curIndex--;
+    }
+
+    public int size() {
+        return curIndex;
+    }
+
+    public int index(int idx) {
+        return arr[idx];
+    }
+}