用 c 语言求解2个未知参数方程的最快算法？

Question

I am counting the value of possible combinations of x and y. It works but when I put big numbers it takes way too long. Do you have any ideas for better algorithm?

ax + by = c

The input of program is a, b and c, which should be non-negative numbers. My code looks like this:

int combs=0;
for(int x=0; x < c; x++) {
    for(int y=0; y < c; y++) {
        if( (a*x) + (b*y) == c) {
            combs++;
        }
    }
}

转载于:https://stackoverflow.com/questions/53250060/the-fastest-algorithm-to-solve-equation-with-2-unknown-parametrs-in-c

Answer 1

A much faster way is to do some math first. ax+by=c => y=(c-ax)/b

int combs=0;
for(int x=0; x < c; x++) {
    int y = (c-a*x)/b;
    if( (a*x) + (b*y) == c)
        combs++;
}