题意可真难懂
给出的length表示一维int数组的长度，那么这个屏幕总共有length * 32位，每一位表示一个像素
而w表示每一行的宽度。例如，如果每行宽度为96，就表示这一行由3个int组成，在一维数组中占用3个元素。由此可以推算出高度为w / 3。
接下来进行位运算就好了。
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| class Solution {
public:
vector<int> drawLine(int length, int w, int x1, int x2, int y) {
int h = length * 32 / 96;
int sh = w / 32;
vector<int> ret(length, 0);
int startLine = x1 / 32 + y * sh;
int endLine = x2 / 32 + y * sh;
x1 %= 32;
x2 %= 32;
for(int i = startLine + 1; i < endLine; ++i)
ret[i] = -1;
if(startLine == endLine)
{
ret[startLine] += static_cast<unsigned int>(1 << (31 - x1)) - 1 - ((1 << (31 - x2)) - 1);
ret[startLine] |= 1 << (31 - x1);
}else
{
ret[startLine] |= 1 << (31 - x1);
ret[startLine] += static_cast<unsigned int>(1 << (31 - x1)) - 1;
ret[endLine] = ~((1 << (31 - x2)) - 1);
}
return ret;
}
};
|
稍微优化一下
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| class Solution {
public:
vector<int> drawLine(int length, int w, int x1, int x2, int y) {
int sh = w / 32;
vector<int> ret(length, 0);
int startLine = x1 / 32 + y * sh;
int endLine = x2 / 32 + y * sh;
x1 %= 32;
x2 %= 32;
for(int i = startLine + 1; i <= endLine; ++i)
ret[i] = -1;
ret[startLine] |= 1 << (31 - x1);
ret[startLine] += static_cast<unsigned int>(1 << (31 - x1)) - 1;
ret[endLine] &= ~((1 << (31 - x2)) - 1);
return ret;
}
};
|