区间DP-矩阵连乘问题

来源：互联网发布：PHP程序员怎么样编辑：程序博客网时间：2024/05/10 19:42
#include <iostream>#include <sstream>#include <stdio.h>#include <algorithm>#include <string.h>#include <stack>#include <queue>#include <set>#include <math.h>/*=======================================矩阵连乘问题dp(i, j) = min( dp(i, k) + dp(k + 1, j) + S);i < k < j;dp(i, i) = 0;========================================*/#define flush(arr, i) memset(arr, i, sizeof(arr))typedef long long int64;using namespace std;const int MAX_ITEM = 128;//const int oo = 0x7fffffff;const int oo = 0x3f3f3f3f;int dp[MAX_ITEM][MAX_ITEM];int w[MAX_ITEM], pos[MAX_ITEM][MAX_ITEM];int DP(int l, int r){    if(l == r)        return 0;    if(dp[l][r])        return dp[l][r];    int ans = oo, tmp = 0;    for(int i = l; i < r; i++)    {        tmp = DP(l, i) + DP(i + 1, r) + w[l - 1] * w[i] * w[r];        if(ans > tmp)        {            ans = tmp;            pos[l][r] = i;        }    }    return dp[l][r] = ans;}void display(int l, int r){    if(l == r)    {        printf("A%d", l);        return;    }    printf("(");    display(l, pos[l][r]);    display(pos[l][r] + 1, r);    printf(")");}int main(){    freopen("0-data.txt", "r", stdin);    int n;    while(scanf("%d", &n) != EOF)    {        flush(dp, 0);        flush(pos, 0);        for(int i = 0; i <= n; i++)            scanf("%d", w + i);        printf("%d\n", DP(1, n));        display(1, n);    }    return 0;}
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