总结
二分查找，容易溢出 用 u64
String chars next 遍历，match匹配值
String into_bytes to vector
Self
1、https://leetcode.cn/problems/valid-perfect-square/submissions/
impl Solution {
pub fn is_perfect_square(num: i32) -> bool {
let mut l:u64 = 0;
let target = num as u64;
let mut r:u64 = target;
let mut mid:u64;
let mut tmp:u64;
while l <= r {
mid = ((r-l)>>1) + l;
tmp = mid * mid;
if tmp > target {
r = mid - 1;
} else if tmp < target {
l = mid + 1;
} else {
return true;
}
}
return false;
}
}
2、https://leetcode.cn/problems/is-subsequence/submissions/
impl Solution {
pub fn is_subsequence(s: String, t: String) -> bool {
let (slen,tlen) = (s.len(), t.len());
let (sbytes,tbytes) = (s.into_bytes(), t.into_bytes());
let mut i :usize = 0;
let mut j :usize = 0;
while i < slen && j < tlen {
if sbytes[i] == tbytes[j] {
i+=1;
}
j +=1;
}
return i == slen;
}
pub fn is_subsequence_v2(s: String, t: String) -> bool {
let mut tchars = t.chars();
for c in s.chars() {
loop {
match tchars.next() {
Some(ct) => {
if c == ct {
break;
}
},
None => {
return false;
}
}
}
}
return true;
}
pub fn is_subsequence_v1(s: String, t: String) -> bool {
let s_len = s.len() as usize;
let mut idxs:usize = 0;
let mut stack:Vec<char> = Vec::with_capacity(s_len);
for c in s.chars() {
stack.push(c);
}
for c in t.chars() {
if idxs < s_len && c == stack[idxs] {
idxs += 1;
}
}
if idxs == s_len {
return true;
}
return false;
}
}
3、https://leetcode.cn/problems/range-sum-query-immutable/submissions/
struct NumArray {
sum :Vec<i32>
}
/**
* `&self` means the method takes an immutable reference.
* If you need a mutable reference, change it to `&mut self` instead.
*/
impl NumArray {
fn new(nums: Vec<i32>) -> Self {
let total = nums.len() as usize;
let mut data:Vec<i32> = Vec::with_capacity(total);
let mut i = 1 as usize;
data.push(nums[0]);
while i < total {
data.push(data[i-1] + nums[i]);
i += 1;
}
Self {
sum :data,
}
}
fn sum_range(&self, left: i32, right: i32) -> i32 {
if left == 0 {
return self.sum[right as usize]
}
return self.sum[right as usize] - self.sum[left as usize - 1]
}
}
/**
* Your NumArray object will be instantiated and called as such:
* let obj = NumArray::new(nums);
* let ret_1: i32 = obj.sum_range(left, right);
*/