51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
/**
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* File: climbing_stairs_dp.c
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* Created Time: 2023-09-19
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* Author: huawuque404 (huawuque404@163.com)
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*/
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#include "../utils/common.h"
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/* Climbing stairs: Dynamic programming */
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int climbingStairsDP(int n) {
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if (n == 1 || n == 2)
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return n;
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// Initialize dp table, used to store subproblem solutions
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int *dp = (int *)malloc((n + 1) * sizeof(int));
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// Initial state: preset the smallest subproblem solution
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dp[1] = 1;
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dp[2] = 2;
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// State transition: gradually solve larger subproblems from smaller ones
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for (int i = 3; i <= n; i++) {
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dp[i] = dp[i - 1] + dp[i - 2];
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}
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int result = dp[n];
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free(dp);
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return result;
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}
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/* Climbing stairs: Space-optimized dynamic programming */
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int climbingStairsDPComp(int n) {
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if (n == 1 || n == 2)
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return n;
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int a = 1, b = 2;
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for (int i = 3; i <= n; i++) {
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int tmp = b;
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b = a + b;
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a = tmp;
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}
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return b;
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}
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/* Driver Code */
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int main() {
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int n = 9;
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int res = climbingStairsDP(n);
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printf("Climbing %d stairs has %d possible solutions\n", n, res);
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res = climbingStairsDPComp(n);
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printf("Climbing %d stairs has %d possible solutions\n", n, res);
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return 0;
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} |