【leetcode】441. Arranging Coins

problem

441. Arranging Coins

solution1:

class Solution {
public:
    int arrangeCoins(int n) {
        long sum = ;
        int curLevel = ;
        while(sum<=n)
        {
            curLevel += ;
            sum += curLevel;
        }
        return (curLevel-);
    }
};

solution2:

class Solution {
public:
    int arrangeCoins(int n) {
        return (int)((sqrt(*(long)n+)-)*0.5);//数学求和公式求解x,注意参数类型是否越界.
    }
};

solution3:

class Solution {
public:
    int arrangeCoins(int n) {
        if(n<=) return n;//err.
        int left = , right = n, mid = ;
        while(left<right)
        {
            mid = left + (right-left)*0.5;
            if((long)mid*(mid+)*0.5 <= n) left = mid+;
            else right = mid;
        }
        return left-;//err.
    }
};

参考

1. Leetcode_441. Arranging Coins;

完