#feat:leetcode p496题题解

src/leetcode/p496/Solution.java

@@ -0,0 +1,46 @@
+package leetcode.p496;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Stack;
+
+/**
+ * @ProjectName: LeetCode
+ * @FileName: Solution
+ * @Author: 杨逸
+ * @Data:2024/10/15 10:37
+ * @Description: https://leetcode.cn/problems/next-greater-element-i/description/
+ *496. 下一个更大元素 I
+ */
+public class Solution {
+    public int[] nextGreaterElement(int[] nums1, int[] nums2) {
+        //记录索引
+        Map<Integer,Integer> map = new HashMap<>();
+        Map<Integer,Integer> nextMaxValueIndex = new HashMap<>();
+        int[] ans = new int[nums1.length];
+        Stack<Integer> stack = new Stack<>();
+
+        for (int i = 0; i < nums2.length; i++) {
+            map.put(nums2[i],i); //记录索引
+            //找下一个更大值的索引
+            while (!stack.isEmpty() && nums2[i] > nums2[stack.peek()]){
+                Integer index = stack.pop();
+                nextMaxValueIndex.put(nums2[index],i);
+            }
+            stack.push(i);
+        }
+
+        for (int i = 0; i < nums1.length; i++) {
+            //索引
+            int index = map.get(nums1[i]);
+            //下一个更大值的索引
+            int nextIndex = nextMaxValueIndex.getOrDefault(nums2[index],-1);
+            if (nextIndex == -1){
+                ans[i] = -1;
+            }else {
+                ans[i] = nums2[nextIndex];
+            }
+        }
+        return ans;
+    }
+}