java实现二分查找

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java实现二分查找

任意数组，先用快速排序进行排序，再二分查找给定数字

public class Test02 {//记录查找的次数static int count = 0;public static void main(String[] args) {int[] nums={51,20,32,45,85,16,47};System.out.println("原数组：");print(nums);//快速排序quickSort(nums,0,nums.length-1);System.out.println("排序后数组：");print(nums);//折半查找（二分查找）int fNum = 2;count++;int n = binaryFind(nums,0,nums.length-1,fNum);if(n==-1){System.out.println("次数组不存在数字："+fNum);}else{System.out.println("要查找的数字为："+fNum);System.out.println("查找次数为："+count);System.out.println("下标为："+n);}}private static int binaryFind(int[] nums, int start, int end, int key) {int middleNum = (end - start)/2 + start;if(key == nums[middleNum]){return middleNum;}if(start>end){return -1;}else if(key>nums[middleNum]){count++;return binaryFind(nums, middleNum+1, end, key);}else{count++;return binaryFind(nums, start, middleNum-1, key);}}private static void quickSort(int[] nums, int start, int end) {int sStart = start;int eEnd = end;int key = nums[start];while(eEnd>sStart){while(eEnd>sStart && nums[eEnd]>=key){eEnd--;}if(nums[eEnd]<=key){int temp = nums[eEnd];nums[eEnd] = nums[sStart];nums[sStart] = temp;}while(eEnd > sStart && nums[sStart]<=key){sStart++;}if(nums[sStart]>=key){int temp = nums[sStart];nums[sStart] = nums[eEnd];nums[eEnd] = temp;}}if(sStart>start){quickSort(nums, start, sStart-1);}if(eEnd<end){quickSort(nums, eEnd+1, end);}}private static void print(int[] nums) {for (int i : nums) {System.out.print(i+" ");}System.out.println();}}

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