参考视频：https://www.bilibili.com/video/BV14j411f7DJ

目录

1.常数阶O(1)

2.对数阶O(IogN)

3.线性阶O(n)

4.线性对数阶O(nlogN)

5.平方阶O(n^2)

6.立方阶O(n^3)

7.K次方阶O(n^k)

8.指数阶(2^n)

9.阶乘O(n!)

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两层for循环        

for (int i = 1; i <= n; i++){
    for (int j = 1; j <=n; j++){
        ×++;
    }
}

for (int i = 1; i<= n; i++){
    x++;
}
for (int i = 1; i <= n; i++){
    for (int j = 1; j <=n; j++){
        ×++;
    }
}

1.常数阶O(1)

int x = O;
int y = 1;
int temp = x;
x=y;
y = temp;

2.对数阶O(IogN)

int i= 1;
while(i< n){
    i = i * 2;
}

循环次数k

2^k=n

k=logn

3.线性阶O(n)

for (int i = 1; i<= n; i++){
    x++;
}

4.线性对数阶O(nlogN)

for(int i= O; i <= n; i++){
    int x = 1;
    while(x < n){
        × = x * 2;
    }
}

5.平方阶O(n^2)

for (int i = 1; i <= n; i++){
    for (int j = 1; j <=m; j++){
        ×++;
    }
}

// O(n*m)

6.立方阶O(n^3)

for (int i = 1; i <= n; i++){
    for (int j = 1; j <=n; j++){
        for (int k = 1; k <=n; k++){
            ×++;
        }
    }
}

7.K次方阶O(n^k)

8.指数阶(2^n)

9.阶乘O(n!)