poj 1276

背包问题的转化~~~

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <cstring>
#include <queue>
#include <cstdio>
#define CLR(arr, what) memset(arr, what, sizeof(arr))
typedef long long ll;
const int MAX = 100005;
const int maxc = 1500;
int top = 0xFFFFFFFF;
using namespace std;
int val[maxc];
int rn;
void add(int numvar, int valvar) {
    int i = 0;
    int orinum = numvar;
    while (numvar) {
        val[rn] = (valvar << i);
        numvar = numvar & (~(1 << i));
        if (0 == numvar) { //最后一位单独处理
            orinum = orinum - ((1 << i) - 1);
            val[rn] = valvar * orinum;
        }
        rn++;
        i++;
    }
}
int dp[MAX];

int main() {
    int cash, t1, t2, n, cur, next;
    while (scanf("%d%d", &cash, &n) != EOF) {
        rn = 0;
        CLR(dp, 0);
        dp[0] = 1;
        for (int i = 0; i < n; i++) {
            scanf("%d%d", &t1, &t2);
            add(t1, t2);
        }
        for (int i = 0; i < rn; i++) {
            for (int j = cash; j >= 0; j--) {
                cur = dp[j];
                if (cur == 1) {
                    next = j + val[i];
                    if (next <= cash) {
                        dp[next] = 1;
                    }
                }
            }
        }
        for (int i = cash; i >= 0; i--) {
            if (dp[i]) {
                cout << i << endl;
                break;
            }
        }

    }
    return 0;
}

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