1.(字符串)-空格替换

如： a b s，替换：%20%20%20a%20b%20s

python：

def replaceBlank(str, length):
    s = ''
    for i in range(length):
        if str[i] == ' ':
            str[i] = '%20'
        s += str[i]
    return s


str = "   a b s"
str = list(str)
a = replaceBlank(str, len(str))
print(a)

c++

int replaceSpace(char string[], int length) {
    int n = 0;
    for (int i=0; i<length; i++)
        if (string[i] == ' ') n++;

    int new_len = length + n*2;
    for (int i=length-1; i>=0; i--) {
        if (string[i] != ' ') {
            string[--new_len] = string[i];
        } else {
            string[--new_len] = '0';
            string[--new_len] = '2';
            string[--new_len] = '%';
        }
    }
    return length + n*2;
}