29.两个整数相除

xiaoxiao2021-02-28  14

Divide Two Integers

问题描述:

Divide two integers without using multiplication, division and mod operator.

If it is overflow, return MAX_INT.

知识补充:

移位运算

a<<1;//移位时,移出的位数全部丢弃,移出的空位补入的数与左移还是右移花接木有关。如果是左移,则规定补入的数全部是0;如果是右移,还与被移位的数据是否带符号有关。若是不带符号数,则补入的数全部为0;若是带符号数,则补入的数全部等于原数的最左端位上的原数(即原符号位) //类似于乘除法,左移一位相当于乘以2.两位乘以4

参考答案:

class Solution { public: int divide(int& n_, int& d_) { long n = abs((long)n_), d = abs((long)d_), res = 0; while(n>=d){ long a = d, count = 1; while((a<<1)<n){a<<=1; count<<=1;} res += count; n -= a; } if(n_>0 ^ d_>0) return -res; return min((long)INT_MAX, max((long)INT_MIN, res)); } };

性能:

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