【HDOJ】2195 Monotone SE Min

简单DP。将[0,1]的浮点数离散化为[0,1000]的整数。最后再除以1000^2.

/* 2195 */
#include <cstdio>
#include <cstring>
#include <cstdlib>

#define MAXN 1000
#define MAXL 205
#define INF  0xfffffff

int dp[MAXL][MAXN+5];
char s[MAXL];

int main() {
    int len;
    int i, j, k;
    int bi, tmp;
    double ans;
    
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
    #endif
    
    while (scanf("%s", s) != EOF) {
        len = strlen(s);
        bi = (s[0]=='0') ? 0:MAXN;
        for (j=0; j<=MAXN; ++j) {
            dp[0][j] = (j-bi)*(j-bi);
        }
        for (i=1; i<len; ++i) {
            bi = (s[i]=='0') ? 0:MAXN;
            tmp = INF;
            for (j=0; j<=MAXN; ++j) {
                if (dp[i-1][j] < tmp)
                    tmp = dp[i-1][j];
                dp[i][j] = tmp + (j-bi)*(j-bi);
            }
        }
        tmp = INF;
        i = len-1;
        for (j=0; j<=MAXN; ++j)
            if (dp[i][j] < tmp)
                tmp = dp[i][j];
        ans = tmp / 1000000.0;
        printf("%.3lf
", ans);
    }
    
    return 0;
}