PAT 1068. Find More Coins

标准10背包

#include <cstdio>

#include <cstdlib>

#include <vector>

#include <algorithm>



using namespace std;

const int ROWS = 10002;

const int COLS = 102;



char dp[ROWS][COLS];



bool dfs(vector<int> &coins, vector<int> &path, int idx, int target) {

    if (dp[idx][target] != -1) {

        return dp[idx][target];

    }

    if (idx >= coins.size()) return false;// should not happen

    if (coins[idx] == target) {

        // we found one

        path.push_back(idx);

        return true;

    }

    if (idx == coins.size() - 1) {

        // no more coins to try

        return false;

    }

    path.push_back(idx);

    // try use current idx coin

    if (coins[idx] < target) {

        if (dfs(coins, path, idx + 1, target - coins[idx])) {

            return true;

        }

    }

    path.pop_back();

    // try not use current idx coin

    if (dfs(coins, path, idx + 1, target)) {

        return true;

    }

    dp[idx][target] = false;

    return dp[idx][target];

}



int main() {

    int N, M;

    scanf("%d%d", &N, &M);

    

    vector<int> coins(N);

    

    for (int i=0; i<N; i++) {

        scanf("%d", &coins[i]);

    }

    sort(coins.begin(), coins.end());

    

    for (int i=0; i<ROWS; i++) {

        for (int j=0; j<COLS; j++) {

            dp[i][j] = -1;

        }

    }

    

    // use current st. j-coins>=0

    //dp[i][j] = dp[i-1][j-coins[i]]

    // not use current

    //dp[i][j] = dp[i-1][j];

    vector<int> path;

    bool res = dfs(coins, path, 0, M);

    int len = path.size();

    if (res) {

        if (len > 0) {

            printf("%d", coins[path[0]]);

        }

        for (int i=1; i<len; i++) {

            printf(" %d", coins[path[i]]);

        }

    } else {

        printf("No Solution");

    }

    return 0;

}