道阻且长,行则将至,走慢一点没关系,不停下就好了.|

Ac_c0mpany丶

园龄:3年7个月粉丝:6关注:3

📂算法
🔖刷题
2021-08-15 18:58阅读: 1611评论: 0推荐: 0

LeetCode常见错误

问题1:

Line 1034: Char 9: runtime error: reference binding to null pointer of type 'int' (stl_vector.h)
数组越界,可能出现下标为-1或者是下标出现size()-1的情况了
vector 的size函数返回vector大小,返回值类型为size_type,Member type size_type is an unsigned integral type,即无符号整数;

vector A;
A.size()-1因为size返回值是无符号类型所以 A.size()-1越界,是个很大的数
所以要用的时候
要么预先定义一个 int n = A.size() - 1;
或者int(A.size() - 1)或者int(A.size()) - 1
或者static_cast(A.size())
以后一定要注意不要使用stl中的size做减法操作。所以写i<size() 不要写 <=size()-1

问题2:

Line 6: Char 48: runtime error: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int' (solution.cpp)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior prog_joined.cpp:15:48

class Solution {
public:
    int mySqrt(int x) {
        int l = 0, r = x;
        while(l < r){
            long long mid = l + r + 1 >> 1;
            if(mid * mid <= x) l = mid;
            else r = mid - 1;
        }
        return l;
    }
};
  1. 当程序中出现整型常量时,默认都是以int类型存储的
  2. 如果算术表达式中出现的所有的数字都是int型的,默认运算结果也是int类型
    l + r + 1 >> 1 当 r 为 int 的最大值时,再+1会超出int范围会报错 正确做法:l + r + 1LL >> 1 把结果转换成long long类型
    int 类型常见的坑

本文作者:Ac_c0mpany丶

本文链接:https://www.cnblogs.com/keyongkang/p/15144374.html

版权声明:本作品采用知识共享署名-非商业性使用-禁止演绎 2.5 中国大陆许可协议进行许可。

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  1. 1 You Are My Sunshine REOL
You Are My Sunshine - REOL
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作曲 : Traditional

You are my sunshine

My only sunshine.

You make me happy

When skies are gray.

You'll never know, dear,

How much I love you.

Please don't take my sunshine away

The other night, dear,

When I lay sleeping

I dreamed I held you in my arms.

When I awoke, dear,

I was mistaken

So I hung my head and cried.

You are my sunshine,

My only sunshine.

You make me happy

When skies are gray.

You'll never know, dear,

How much I love you.

Please don't take my sunshine away.

You are my sunshine,

My only sunshine

You make me happy

When skies are gray.

You'll never know, dear

How much I love you

Please don't take my sunshine away

Please don't take my sunshine away.

Please don't take my sunshine away.