1237. Find out the positive combination of the given square One question daily

topic：

1237. Find out the positive combination of the given square.md

Thought：

Want to be complicated，It turned out to be intended to recover，Then constantly find out the solution。Then Ling Shen tells us：In fact, this question is a double pointer，One on the far left is on the right。
Monoly increase function，XCan only increase，YCan only reduce，So iff(x,y)<z，ExplainXIt’s time to increase，vice versa。

Because you need to continue to find after equal，So continue f(x,y)<zTalent operation，After modificationf(x+1,y)>f(x,y)=z，Depending on the circumstances 2，Can y minus one。

Code：

class Solution:
    def findSolution(self, customfunction: 'CustomFunction', z: int) -> List[List[int]]:
        ans = []
        x, y = 1, 1000
        while x <= 1000 and y:
            res = customfunction.f(x, y)
            if res < z:
                x += 1
            elif res > z:
                y -= 1
            else:
                ans.append([x, y])
                x += 1
                y -= 1
        return ans

IF