leetcode

Dynamic Programming I: Day 1

2 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/ Problems/0509.cpp b/ Problems/0509.cpp

@@ -1,3 +1,4 @@

// memorization approach

class Solution { public: int fib(int n) {

@@ -8,3 +9,18 @@ public: return f[n]; } };

// optimized, memorize only the previous two values

class Solution {

public:

int fib(int n) {

if (n == 0) return 0;

int a = 0, b = 1;

for (int i = 2; i <= n; i++) {

int tmp = a + b;

a = b;

b = tmp;

}

return b;

}

};

diff --git a/ Problems/1137.cpp b/ Problems/1137.cpp

@@ -1,3 +1,4 @@

// memorization approach

class Solution { public: int tribonacci(int n) {

@@ -9,3 +10,20 @@ public: return f[n]; } };

// optimized, memorize only the previous three values

class Solution {

public:

int tribonacci(int n) {

if (n == 0) return 0;

if (n == 1) return 1;

int a = 0, b = 1, c = 1;

for (int i = 3; i <= n; i++) {

int tmp = a + b + c;

a = b;

b = c;

c = tmp;

}

return c;

}

};