【动态规划】【01背包入门】PKU 3624 Charm Bracelet

#include <stdio.h> #include <string.h> #define MAX_N 3500 #define MAX_W 13000 struct things { int weight; int value; }; int GetMax(int a, int b) { return a>b?a:b; } things t[MAX_N]; int w[2][MAX_W]; int main() { int m,n; int i,j; int pos; while (scanf("%d%d", &n, &m) != EOF) { memset(w, 0, sizeof(w)); for (i=1;i<=n;i++) scanf("%d%d", &t[i].weight, &t[i].value); pos = 0; for (i=1;i<=n;i++) { for (j=1;j<=m;j++) if (j>=t[i].weight) w[i%2][j] = GetMax(w[pos][j], w[pos][j-t[i].weight] + t[i].value); else w[i%2][j] = w[pos][j]; pos++; pos %= 2; } printf("%d/n", w[pos][m]); } return 0; } /* Charm Bracelet Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 3354 Accepted: 1498 Description Bessie has gone to the mall's jewelry store and spies a charm bracelet. Of course, she'd like to fill it with the best charms possible from the N (1 ≤ N ≤ 3,402) available charms. Each charm i in the supplied list has a weight Wi (1 ≤ Wi ≤ 400), a 'desirability' factor Di (1 ≤ Di ≤ 100), and can be used at most once. Bessie can only support a charm bracelet whose weight is no more than M (1 ≤ M ≤ 12,880). Given that weight limit as a constraint and a list of the charms with their weights and desirability rating, deduce the maximum possible sum of ratings. Input * Line 1: Two space-separated integers: N and M * Lines 2..N+1: Line i+1 describes charm i with two space-separated integers: Wi and Di Output * Line 1: A single integer that is the greatest sum of charm desirabilities that can be achieved given the weight constraints Sample Input 4 6 1 4 2 6 3 12 2 7 Sample Output 23 */