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Implement int sqrt(int x).
Compute and return the square root of x, where x is guaranteed to be a non-negative integer.
Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.
Example 1:
Input: 4
Output: 2
Example 2:
Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842…, and since the decimal part is truncated, 2 is returned.
难度:easy
题目:实现 sqrt. 计算并返回 x 的开方,x 保证非负整。由于返回的类型是整数,十进制数只返回整数部分。
Runtime: 22 ms, faster than 30.19% of Java online submissions for Sqrt(x).Memory Usage: 27 MB, less than 99.23% of Java online submissions for Sqrt(x).
class Solution {
public int mySqrt(int x) {
if (0 == x) {
return x;
}
int left = 1, right = x, mid = 0, lastMid = 0;
while (left <= right) {
mid = left + (right – left) / 2;
if (mid > x / mid) {
right = mid – 1;
} else {
left = mid + 1;
lastMid = mid;
}
}
return lastMid;
}
}