LeetCode

最新推荐文章于 2025-07-29 19:45:28 发布

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最新推荐文章于 2025-07-29 19:45:28 发布

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文章标签： leetcode

本文链接：https://blog.youkuaiyun.com/PPDY93/article/details/115533228

本文档介绍了如何使用Java实现字符串中的空格替换为%20，并探讨了二分查找算法的基本应用。通过实例展示了Solution类中replaceSpace方法和search方法的操作细节。

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剑指 Offer 05. 替换空格

请实现一个函数，把字符串 s 中的每个空格替换成"%20"。
输入：s = “We are happy.”
输出：“We%20are%20happy.”

class Solution {
    public String replaceSpace(String s) {
        int length  = s.length();
        char array[] = new char[length * 3];
        int size = 0;
        for(int i = 0 ; i < length ; i++){
            char c = s.charAt(i);
            if(c == ' '){
               array[size++] = '%';
               array[size++] = '2';
               array[size++] = '0';
            }else{
               array[size++] = c;
            }
        }
        String newStr = new String(array,0,size);
        return newStr;
    }
}

704.二分查找

class Solution {
    public int search(int[] nums, int target) {
        int left = 0, right = nums.length - 1;
        while(left<=right) {
            int mid = left + (right - left) / 2;
            if(nums[mid] == target) {
                return mid;
            } else if(nums[mid] > target) {
                right = mid - 1;
            } else {
                left  = mid + 1;
            }
        }
        return -1;
    }
}

class Solution {
	public int search(int[] nums, int target) {
		int left = 0;
		int right = nums.length - 1;
		int mid = (left + right) / 2;
		while (nums[mid] != target) {
			if (target < nums[mid]) {
				right = mid - 1;
			}
			if (target > nums[mid]) {
				left = mid + 1;
			}
			if (left > right) {
				mid = -1;
				break;
			}
			mid = (left + right) / 2;
		}
		return mid;
	}
}