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Cracking The Coding Interview5.1

2014-04-18 01:17 232 查看
//You are given two 32-bit numbers, N and M, and two bit positions, i and j. Write a method to set all bits between i and j in N equal to M (e.g., M becomes a substring of N located at i and starting at j).
//
//EXAMPLE:
//
//Input: N = 10000000000, M = 10101, i = 2, j = 6
//
//Output: N = 10001010100

#include <iostream>
#include <vector>
using namespace std;
/***纯粹是计算题***/
int mset(int N, int M, int i, int j)
{
int t = 1;
t =t << j-i+1;
t --;//得到0000 0000 0001 1111
t=t<<i;
t = ~t;//得到1111 1111 1100 00011
M= M<<i;
int K = t & N;//将N对应位置set为0
K = K|M;
return K;
}

void print(int p)
{
vector<int> v;
for (int k = 0;k<32; k++)
{
int t = p&1;
v.push_back(t);
p=p>>1;
}
for (int i = v.size()-1;i>-1; i--)
{
cout<<v[i]<<" ";
}
cout<<endl;
}
int main()
{
int n = 1<<10, m = 21;
print(n);
print(m);
cout<<"====================================================================="<<endl;
for (int t = 0;t<20;t++)
{
int ss= mset(n, m,t,t+4);
print(ss);
}

return 0;
}
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