leetcode [#67]

目录

• 1. 题目
• 2. 解决方案
• 3. 注意事项

题目

Given two binary strings, return their sum (also a binary string).

Example
a = “11”
b = “1”
Return “100”.

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解决方案

public class Solution {
    public String addBinary(String a, String b) {
        int len1 = a.length();
        int len2 = b.length();
        int delta = Math.abs(len1 - len2);
        int max = Math.max(len1, len2);
        int[] intVal1 = new int[max];
        int[] intVal2 = new int[max];
        if(len1 >= len2){
            for(int i = 0; i < max; i++){
                intVal1[i] = Integer.parseInt(String.valueOf(a.charAt(i)));
            }
            for(int j = 0; j < max; j++){
                if(j < delta){
                    intVal2[j] = 0;
                } else {
                    intVal2[j] = Integer.parseInt(String.valueOf(b.charAt(j - delta)));
                }
            }
        } else {
            for(int i = 0; i < max; i++){
                intVal1[i] = Integer.parseInt(String.valueOf(b.charAt(i)));
            }
            for(int j = 0; j < max; j++){
                if(j < delta){
                    intVal2[j] = 0;
                } else {
                    intVal2[j] = Integer.parseInt(String.valueOf(a.charAt(j - delta)));
                }
            }
        }
        StringBuilder builder = new StringBuilder("");
        handle(max, 0, intVal1, intVal2, builder);
        return builder.reverse().toString();
    }
    private static void handle(int max, int more, int[] val1, int[] val2, StringBuilder builder){
        int temp = 0;
        if(max >= 1){
            temp = val1[max - 1] + val2[max - 1] + more;
        } else {
            temp = val1[0] + val2[0] + more;
        }
        if(max-1 > 0){
            if(temp <= 1){
                builder.append(Integer.toString(temp));
                handle(--max, 0, val1, val2, builder);
            } else {
                builder.append(Integer.toString(temp % 2));
                handle(--max, 1, val1, val2, builder);
            }
        } else {
            if(temp <= 1){
                builder.append(Integer.toString(temp));
            } else {
                builder.append(Integer.toString(temp % 2));
                builder.append("1");
            }
        }
    }
}

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注意事项

1. 思路基本与leetcode [#415]相同。只不过此处变成了二进制。