leetcode

Dynamic Programming I: Day 2

2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/ Problems/0070.cpp b/ Problems/0070.cpp

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

// memorization approach

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

@@ -8,7 +9,11 @@ public: return vec[n]; }

}

// optimized, memorize only the previous two values

class Solution {

public:

int climbStairs(int n) { int first = 1, second = 1; for (int i = 2; i <= n; i++) {

diff --git a/ Problems/0746.cpp b/ Problems/0746.cpp

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

// memorization approach

class Solution { public: int minCostClimbingStairs(vector<int> &cost) {

@@ -6,14 +7,17 @@ public: vec[i] = min(vec[i - 1] + cost[i - 1], vec[i - 2] + cost[i - 2]); return vec[cost.size()]; }

};

// optimized, memorize only the previous two values

class Solution {

public:

int minCostClimbingStairs(vector<int> &cost) { int first = cost[0], second = cost[1];

if (cost.size() <= 2) return min(first, second);

for (int i = 2; i < cost.size(); i++) {

int cur = cost[i] + min(first, second);

int crnt = cost[i] + min(first, second);

first = second;

second = cur;

second = crnt;

} return min(first, second); }