leetcode-67-Add Binary

标签：leetcode

                                           Add Binary

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

For example,
a = "11"
b = "1"
Return "100".

两字符串表示的2进制数。求它们的和。

直接模拟，从最后一位开始每一位都相加，结果保存在栈中。

class Solution {
public:
    string addBinary(string a, string b) {
        stack<int>s;
        int n = a.size() - 1,m = b.size() - 1;
        int add = 0; //进位 
        while (n >= 0 && m >= 0) {    // 计算每一位的结果，存在栈中
            if (a[n] == '0' && b[m] == '0') {
                if (add == 1) s.push('1');
                else s.push('0');
                add = 0;
            }
            else if (a[n] == '0' && b[m] == '1' ||a[n] == '1' && b[m] == '0') {
                if (add == 1) {s.push('0');add = 1;}
                else {s.push('1');add = 0;}
            }
            else {
                if (add == 1) s.push('1');
                else s.push('0');
                add = 1;
            }
            n--;
            m--;
        }
        // 两字符串有一字符串为空 则另作讨论
        if (n < 0 && m < 0) {
            if (add == 1) s.push('1');
        }
        else if (n >= 0 && m < 0) {
            while (n >= 0) {
                if (a[n] == '1') {
                    if (add == 1) {s.push('0');add = 1;}
                    else {s.push('1');add = 0;}
                }
                else if (a[n] == '0') {
                    if (add == 1 ) s.push('1');
                    else s.push('0');
                    add = 0;
                }
                n--;
            }
            if (add == 1) s.push('1');
        }
        else if (n < 0 && m >= 0) {
            while (m >= 0) {
                if (b[m] == '1') {
                    if (add == 1) {s.push('0');add = 1;}
                    else {s.push('1');add = 0;}
                }
                else if (b[m] == '0') {
                    if (add == 1 ) s.push('1');
                    else s.push('0');
                    add = 0;
                }
                m--;
            }
            if (add == 1) s.push('1');
        }
        string c;
        while(!s.empty()) {  // 每一位的结果，从栈中取出，存入string中
            c += s.top();
            s.pop();
        }
        return c;
    }
};

leetcode-67-Add Binary

标签：leetcode

原文地址：http://blog.csdn.net/u014705854/article/details/47260227