45 lines
1.4 KiB
Java
45 lines
1.4 KiB
Java
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import java.util.Arrays;
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public class double_pointer {
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public static void main(String[] args) {
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//int[] arr = {3,2,2,3};
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//int res = removeElement(arr, 3);
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//System.out.println("移除元素后的有效长度"+res+" :"+" 移除过后数组内的数据"+ Arrays.toString(arr));
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int[] arr = {2,7,11,15};
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int[] result = twoSum(arr, 9);
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System.out.println("结果集:"+ Arrays.toString(result));
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}
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//快慢指针案例
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static int removeElement(int[] nums, int val) {
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int fast = 0, slow = 0;
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while (fast < nums.length) {
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//如果等于target那么fast++，slow记录命中的下表等到fast找到不等于的时候替换slow
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if (nums[fast] != val) {
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nums[slow] = nums[fast];
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slow++;
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}
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fast++;
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}
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return slow;
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}
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//相向左右指针案例
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static int[] twoSum(int[] nums, int target) {
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// 一左一右两个指针相向而行
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int left = 0, right = nums.length - 1;
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while (left < right) {
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int sum = nums[left] + nums[right];
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if (sum == target) {
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return new int[]{left, right};
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} else if (sum < target) {
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left++; // 让 sum 大一点
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} else if (sum > target) {
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right--; // 让 sum 小一点
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}
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}
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return new int[]{-1, -1};
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}
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}
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