两个整数相除

将两个整数相除,要求不使用乘法、除法和 mod 运算符。

如果溢出,返回 2147483647 。
class Solution {
public:
    int divide(int dividend, int divisor) {
        // Write your code here
        const int OVER_FLOW = 2147483647; 
        
        long long divd = dividend;
        long long divr = divisor;
        
        if (divr == 0) {
            return OVER_FLOW;
        }

        int flag = 1;
        if (divd < 0 && divr > 0  || divd > 0 && divr < 0) {
            flag = -1;
        }
        divd  = abs(divd);
        divr = abs(divr);
        
        long long ret = 0;
        
        while (divr <= divd) {
            long long cnt = 1;
            long long tmp = divr;
            while (tmp <= divd) {
                divd -= tmp;
                ret += cnt;
                cnt <<= 1;
                tmp <<= 1;
            }
        }
        
        ret *= flag; 
        
        if (ret > INT_MAX || ret < INT_MIN) {
            return OVER_FLOW;
        }
        return ret;
    }
    
};
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