2024/9/13 Hot100 二分查找

src/main/java/com/cool/hot100/binary_search/Num34.java

@@ -0,0 +1,44 @@
+package com.cool.hot100.binary_search;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/13/16:02
+ * DayNumber 4
+ * Hard 2
+ * Level ?
+ */
+public class Num34 {
+    public int[] searchRange(int[] nums, int target) {
+        int index = binarySearch(nums, target);
+        if(index==nums.length||nums[index]!=target){
+            return new int[]{-1,-1};
+        }
+        int end=binarySearch(nums,target+1)-1;
+        return new int[]{index,end};
+    }
+
+    private int binarySearch(int[] nums, int target) {
+        int left=0;
+        int right=nums.length-1;
+        while (left <= right) {
+            int mid =left+(right-left)/2;
+            if(target>nums[mid]){
+                left=mid+1;
+            }else{
+                right=mid-1;
+            }
+        }
+        return left;
+    }
+
+    @Test
+    public void test() {
+        searchRange(new int[]{5,7,7,8,8,10}, 6);
+    }
+}

src/main/java/com/cool/hot100/binary_search/Num74.java

@@ -0,0 +1,42 @@
+package com.cool.hot100.binary_search;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/13/15:35
+ * DayNumber 3
+ * Hard 2
+ * Level ?
+ */
+public class Num74 {
+
+    public boolean searchMatrix(int[][] matrix, int target) {
+        int rowLen=matrix.length;
+        if(rowLen==0){
+            return false;
+        }
+        int index=0;
+        int colLen=matrix[0].length;
+        for(int i=1;i<rowLen;i++){
+            if(target<matrix[i][0]){
+                break;
+            }
+            index=i;
+        }
+        int left=0;
+        int right=colLen;
+        while(left<right){
+            int mid=(left+right)/2;
+            if(target<matrix[index][mid]){
+                right=mid;
+            }else if(target>matrix[index][mid]){
+                left=mid+1;
+            }else{
+                return true;
+            }
+        }
+        return false;
+    }
+
+}